Clean up module documentation (#36909)

* Clean up module documentation

This PR includes:
- Removal of `default: None` (and variations)
- Removal of `required: false`
- Fixing booleans and `type: bool` where required

* Fix remaining (new) validation issues

lib/ansible/modules/system/sysctl.py

@@ -26,13 +26,10 @@ options:
         description:
             - The dot-separated path (aka I(key)) specifying the sysctl variable.
         required: true
-        default: null
         aliases: [ 'key' ]
     value:
         description:
             - Desired value of the sysctl key.
-        required: false
-        default: null
         aliases: [ 'val' ]
     state:
         description:
@@ -42,29 +39,25 @@ options:
     ignoreerrors:
         description:
             - Use this option to ignore errors about unknown keys.
-        choices: [ "yes", "no" ]
-        default: no
+        type: bool
+        default: 'no'
     reload:
         description:
             - If C(yes), performs a I(/sbin/sysctl -p) if the C(sysctl_file) is
               updated. If C(no), does not reload I(sysctl) even if the
               C(sysctl_file) is updated.
-        choices: [ "yes", "no" ]
-        default: "yes"
+        type: bool
+        default: 'yes'
     sysctl_file:
         description:
             - Specifies the absolute path to C(sysctl.conf), if not C(/etc/sysctl.conf).
-        required: false
         default: /etc/sysctl.conf
     sysctl_set:
         description:
             - Verify token value with the sysctl command and set with -w if necessary
-        choices: [ "yes", "no" ]
-        required: false
+        type: bool
+        default: 'no'
         version_added: 1.5
-        default: False
-notes: []
-requirements: []
 author: "David CHANIAL (@davixx) <david.chanial@gmail.com>"
 '''