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/source_control/github_key.py

@@ -30,21 +30,17 @@ options:
   pubkey:
     description:
       - SSH public key value. Required when C(state=present).
-    required: false
-    default: none
   state:
     description:
       - Whether to remove a key, ensure that it exists, or update its value.
     choices: ['present', 'absent']
     default: 'present'
-    required: false
   force:
     description:
       - The default is C(yes), which will replace the existing remote key
         if it's different than C(pubkey). If C(no), the key will only be
         set if no key with the given C(name) exists.
-    required: false
-    choices: ['yes', 'no']
+    type: bool
     default: 'yes'
 
 author: Robert Estelle (@erydo)