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/network/panos/panos_commit.py

@@ -42,23 +42,19 @@ options:
     username:
         description:
             - username for authentication
-        required: false
         default: "admin"
     interval:
         description:
             - interval for checking commit job
-        required: false
         default: 0.5
     timeout:
         description:
             - timeout for commit job
-        required: false
-        default: None
     sync:
         description:
             - if commit should be synchronous
-        required: false
-        default: true
+        type: bool
+        default: 'yes'
 '''
 
 EXAMPLES = '''