doc: clean-up Development Environment and Tools page

GitHub labels were hard to visually parse so use guilabel role to make them
stand out more, and put them in tabular format.
Other minor cosmetic tweaks

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>

doc/project/dev_env_and_tools.rst

@@ -210,10 +210,10 @@ Developers are expected to fix issues and rework their patches and submit again.
 
 The CI infrastructure currently runs the following tests:
 
-- Run ''checkpatch'' for code style issues (can vote -1 on errors; see note)
+- Run ``checkpatch`` for code style issues (can vote -1 on errors; see note)
 - Gitlint: Git commit style based on project requirements
 - License Check: Check for conflicting licenses
-- Run ''twister'' script
+- Run ``twister`` script
 
   - Run kernel tests in QEMU (can vote -1 on errors)
   - Build various samples for different boards (can vote -1 on errors)
@@ -222,10 +222,12 @@ The CI infrastructure currently runs the following tests:
 
 .. note::
 
-   ''checkpatch'' is a Perl script that uses regular expressions to
+   ``checkpatch`` is a Perl script that uses regular expressions to
    extract information that requires a C language parser to process
    accurately.  As such it sometimes issues false positives.  Known
-   cases include constructs like::
+   cases include constructs like:
+
+    .. code-block:: c
 
       static uint8_t __aligned(PAGE_SIZE) page_pool[PAGE_SIZE * POOL_PAGES];
       IOPCTL_Type *base = config->base;
@@ -264,45 +266,42 @@ These are the labels we currently have, grouped by applicability:
 Labels applicable to issues only
 ================================
 
-* *priority: {high|medium|low}*
+.. list-table::
+   :header-rows: 1
 
-To classify the impact and importance of a bug or
+   * - Label
+     - Description
+
+   * - :guilabel:`priority: {high|medium|low}`
+     - To classify the impact and importance of a bug or
        :ref:`feature <feature-tracking>`.
 
        Note: Issue priorities are generally set or changed during the bug-triage or TSC
        meetings.
 
-* *Regression*
+   * - :guilabel:`Regression`
+     - Something, which was working, but does not anymore (bug subtype).
 
-Something, which was working, but does not anymore (bug subtype).
+   * - :guilabel:`Enhancement`
+     - Changes/Updates/Additions to existing :ref:`features <feature-tracking>`.
 
-* *Enhancement*
+   * - :guilabel:`Feature request`
+     - A request for a new :ref:`feature <feature-tracking>`.
 
-Changes/Updates/Additions to existing :ref:`features <feature-tracking>`.
+   * - :guilabel:`Feature`
+     - A :ref:`planned feature<feature-tracking>` with a milestone.
 
-* *Feature request*
+   * - :guilabel:`Hardware Support`
+     - Covers porting an existing feature (including Zephyr itself) to new hardware.
 
-A request for a new :ref:`feature <feature-tracking>`.
+   * - :guilabel:`Duplicate`
+     - This issue is a duplicate of another issue (please specify).
 
-* *Feature*
+   * - :guilabel:`Good first issue`
+     - Good for a first time contributor to take.
 
-A :ref:`planned feature<feature-tracking>` with a milestone.
+   * - :guilabel:`Release Notes`
-
+     - Issues that need to be mentioned in release notes as known issues with
-* *Hardware Support*
-
-Covers porting an existing feature (including Zephyr itself) to new hardware.
-
-* *Duplicate*
-
-This issue is a duplicate of another issue (please specify).
-
-* *Good first issue*
-
-Good for a first time contributor to take.
-
-* *Release Notes*
-
-Issues that need to be mentioned in release notes as known issues with
        additional information.
 
 Any issue must be classified and labeled as either *Bug*, *Enhancement*, *RFC*,
@@ -315,36 +314,37 @@ Labels applicable to pull requests only
 
 The issue or PR describes a change to a stable API.
 
-* *Hotfix*
+.. list-table::
+   :header-rows: 1
 
-Fix for an issue blocking development.
+   * - Label
+     - Description
 
-* *Trivial*
+   * - :guilabel:`Hotfix`
+     - Fix for an issue blocking development.
 
-* *Maintainer*
+   * - :guilabel:`Trivial`
+     - Simple changes that can have shorter review time and be reviewed by anyone, i.e. typos,
+       straightforward one-liner bug fixes, etc.
 
-Maintainer review required.
+   * - :guilabel:`Maintainer`
+     - Maintainer review required.
 
-* *Security Review*
+   * - :guilabel:`Security Review`
+     - To be reviewed by a security expert.
 
-To be reviewed by a security expert.
+   * - :guilabel:`DNM`
-
+     - This PR should not be merged (Do Not Merge). For work in progress, GitHub
-* *DNM*
-
-This PR should not be merged (Do Not Merge). For work in progress, GitHub
        "draft" PRs are preferred.
 
-* *Needs review*
+   * - :guilabel:`Needs review`
+     - The PR needs attention from the maintainers.
 
-The PR needs attention from the maintainers.
+   * - :guilabel:`Backport`
+     - The PR is a backport or should be backported.
 
-* *Backport*
+   * - :guilabel:`Licensing`
-
+     - The PR has licensing issues which require a licensing expert to review it.
-The PR is a backport or should be backported.
-
-* *Licensing*
-
-The PR has licensing issues which require a licensing expert to review it.
 
 .. note::
    For all labels applicable to PRs: Please note that the label, together with
@@ -355,74 +355,66 @@ The PR has licensing issues which require a licensing expert to review it.
 Labels applicable to both pull requests and issues
 ==================================================
 
-* *area: **
+.. list-table::
+   :header-rows: 1
 
-Indicates Zephyr subsystems (e.g, *area: Kernel*, *area: I2C*,
+   * - Label
-*area: Memory Management*), project functions (e.g., *area: Debugging*,
+     - Description
-*area: Documentation*, *area: Process*), or other categories (e.g.,
+
-*area: Coding Style*, *area: MISRA-C*) affected by the bug or the pull request.
+   * - :guilabel:`area: {area-name}`
+     - Indicates Zephyr subsystems (e.g, :guilabel:`area: Kernel`, :guilabel:`area: I2C`,
+       :guilabel:`area: Memory Management`), project functions (e.g., :guilabel:`area: Debugging`,
+       :guilabel:`area: Documentation`, :guilabel:`area: Process`), or other categories (e.g.,
+       :guilabel:`area: Coding Style`, :guilabel:`area: MISRA-C`) affected by the bug or the pull request.
 
        An area maintainer should be able to filter by an area label and find all issues
        and PRs which relate to that area.
 
-* *platform: **
+   * - :guilabel:`platform: {platform-name}`
+     - An issue or PR which affects only a particular platform.
 
-An issue or PR which affects only a particular platform.
+   * - :guilabel:`dev-review`
-
+     - The issue is to be discussed in the following `dev-review`_ if time
-* *dev-review*
-
-The issue is to be discussed in the following `dev-review`_ if time
        permits.
 
        .. _`dev-review`: https://github.com/zephyrproject-rtos/zephyr/wiki/Zephyr-Committee-and-Working-Group-Meetings#zephyr-dev-meeting
 
-* *TSC*
+   * - :guilabel:`TSC`
-
+     - TSC stands for Technical Steering Committee. The issue is to be discussed in the
-TSC stands for Technical Steering Committee. The issue is to be discussed in the
        following `TSC meeting`_ if time permits.
 
        .. _`TSC meeting`: https://github.com/zephyrproject-rtos/zephyr/wiki/Zephyr-Committee-and-Working-Group-Meetings#technical-steering-committee-tsc
 
-* *Breaking API Change*
+   * - :guilabel:`Breaking API Change`
-
+     - The issue or PR describes a breaking change to a stable API. See additional information
-The issue or PR describes a breaking change to a stable API. See additional information
        in :ref:`breaking_api_changes`.
 
-* *Bug*
+   * - :guilabel:`bug`
+     - The issue is a bug, or the PR is fixing a bug.
 
-The issue is a bug, or the PR is fixing a bug.
+   * - :guilabel:`Coverity`
+     - A Coverity detected issue or its fix.
 
-* *Coverity*
+   * - :guilabel:`Waiting for response`
-
+     - The Zephyr developers are waiting for the submitter to respond to a question, or
-A Coverity detected issue or its fix.
-
-* *Waiting for response*
-
-The Zephyr developers are waiting for the submitter to respond to a question, or
        address an issue.
 
-* *Blocked*
+   * - :guilabel:`Blocked`
+     - Blocked by another PR or issue.
 
-Blocked by another PR or issue.
+   * - :guilabel:`Stale`
+     - An issue or a PR which seems abandoned, and requires attention by the author.
 
-* *Stale*
+   * - :guilabel:`In progress`
-
+     - For PRs: is work in progress and should not be merged yet. For issues: Is being
-An issue or a PR which seems abandoned, and requires attention by the author.
-
-* *In progress*
-
-For PRs: is work in progress and should not be merged yet. For issues: Is being
        worked on.
 
-* *RFC*
+   * - :guilabel:`RFC`
-
+     - The author would like input from the community. For a PR it should be considered
-The author would like input from the community. For a PR it should be considered
        a draft.
 
-* *LTS*
+   * - :guilabel:`LTS`
+     - Long term release branch related.
 
-Long term release branch related.
+   * - :guilabel:`EXT`
-
+     - Related to an external component.
-* *EXT*
-
-Related to an external component.