doc: enable vcs_link extension

Enable the vcs_link extension so that pages contain "Open on Github"
link at the top.

Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>

doc/_templates/breadcrumbs.html

@@ -17,4 +17,12 @@
   <li class="wy-breadcrumbs-aside">
     <dark-mode-toggle id="dark-mode-toggle" appearance="toggle" permanent="true"/>
   </li>
+  <li class="wy-breadcrumbs-aside">
+    {%- if display_vcs_link %}
+      {% set vcs_url = pagename | vcs_link_get_url %}
+      {% if vcs_url %}
+        <a href="{{ vcs_url }}" class="fa fa-github"> {{ _('Open on GitHub') }}</a>
+      {% endif %}
+    {% endif %}
+  </li>
 {%- endblock %}

doc/conf.py

@@ -80,6 +80,7 @@ extensions = [
     "sphinx_tabs.tabs",
     "zephyr.warnings_filter",
     "zephyr.doxyrunner",
+    "zephyr.vcs_link",
     "notfound.extension",
     "zephyr.external_content",
 ]
@@ -149,6 +150,7 @@ html_context = {
         ("2.3.0", "/2.3.0/"),
         ("1.14.1", "/1.14.1/"),
     ),
+    "display_vcs_link": True,
 }
 
 # -- Options for LaTeX output ---------------------------------------------
@@ -221,6 +223,21 @@ warnings_filter_silent = False
 
 notfound_urls_prefix = f"/{version}/" if is_release else "/latest/"
 
+# -- Options for zephyr.vcs_link ------------------------------------------
+
+vcs_link_version = f"v{version}" if is_release else "main"
+vcs_link_base_url = f"https://github.com/zephyrproject-rtos/zephyr/blob/{vcs_link_version}"
+vcs_link_prefixes = {
+    "samples/.*": "",
+    "boards/.*": "",
+    ".*": "doc",
+}
+vcs_link_exclude = [
+    "reference/kconfig.*",
+    "reference/devicetree/bindings.*",
+    "reference/devicetree/compatibles.*",
+]
+
 # -- Options for zephyr.external_content ----------------------------------
 
 external_content_contents = [