doc: fix misspellings in docs

Scan and fix misspellings missed during regular reviews.

Signed-off-by: David B. Kinder <david.b.kinder@intel.com>

doc/application/application.rst

@@ -402,11 +402,11 @@ where the ``boards`` directory hosts the board you are building for:
 
    .
    ├── boards
-   │   └── x86
-   │       └── my_custom_board
-   │           ├── doc
-   │           │   └── img
-   │           └── support
+   │   └── x86
+   │       └── my_custom_board
+   │           ├── doc
+   │           │   └── img
+   │           └── support
    └── src
 
 

doc/security/sensor-threat.rst

@@ -83,7 +83,7 @@ included in this model:
 
 5. **Current date/time**. TLS certificate verification requires
    knowledge of the current date and time in order to determine if the
-   current time falls within the certificate’s current validity time.
+   current time falls within the certificate's current validity time.
    Also, token based client authentication will generally require the
    client to sign a message containing a time window that the token is
    valid. Certificate validation requires the device's notion of date and
@@ -133,7 +133,7 @@ In addition to assets, the threat model also considers the locations
 where data or assets are communicated between entities of the system.
 
 1. **Flash contents**. The flash device contains several regions. The
-   contents of flash can be modified programmatically by the SoC’s CPU.
+   contents of flash can be modified programmatically by the SoC's CPU.
 
    a. **The bootloader**. As described in the Assets section, the
       bootloader is a small section of the flash device containing the
@@ -234,7 +234,7 @@ where data or assets are communicated between entities of the system.
            complies with this restriction.
 
       iii. **Validity period**. The validity period of all presented
-           certificates shall be checked against the device’s best
+           certificates shall be checked against the device's best
            notion of the current time.
 
    c. **Client authentication**. The client shall authenticate itself to
@@ -257,7 +257,7 @@ where data or assets are communicated between entities of the system.
           the MQTT CONNECT packet. However, the secret itself must not
           be transmitted in this packet. Instead, a token-based
           protocol, such as
-          `RFC7519 <https://tools.ietf.org/html/rfc7519>`__\ ’s JSON Web
+          `RFC7519 <https://tools.ietf.org/html/rfc7519>`__\ 's JSON Web
           Token (JWT) can be used. These tokens will generally have a
           small validity period (e.g. 1 hour), to prevent them from
           being reused if they are intercepted. The token shall not be

doc/subsystems/shell.rst

@@ -83,7 +83,7 @@ Here are the Kernel module shell commands:
  Displays the system uptime in milliseconds
 
 ``cycles``
- Displays the current time (in cycles), as measured by the system’s hardware clock
+ Displays the current time (in cycles), as measured by the system's hardware clock
 
 ``threads``
  Displays information about the running threads (if