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/notification/rocketchat.py

@@ -38,7 +38,6 @@ options:
   protocol:
     description:
       - Specify the protocol used to send notification messages before the webhook url. (i.e. http or https)
-    required: false
     default: https
     choices:
       - 'http'
@@ -46,34 +45,25 @@ options:
   msg:
     description:
       - Message to be sent.
-    required: false
-    default: None
   channel:
     description:
       - Channel to send the message to. If absent, the message goes to the channel selected for the I(token)
         specified during the creation of webhook.
-    required: false
-    default: None
   username:
     description:
       - This is the sender of the message.
-    required: false
     default: "Ansible"
   icon_url:
     description:
       - URL for the message sender's icon.
-    required: false
     default: "https://www.ansible.com/favicon.ico"
   icon_emoji:
     description:
       - Emoji for the message sender. The representation for the available emojis can be
         got from Rocket Chat. (for example :thumbsup:) (if I(icon_emoji) is set, I(icon_url) will not be used)
-    required: false
-    default: None
   link_names:
     description:
       - Automatically create links for channels and usernames in I(msg).
-    required: false
     default: 1
     choices:
       - 1
@@ -82,15 +72,11 @@ options:
     description:
       - If C(no), SSL certificates will not be validated. This should only be used
         on personally controlled sites using self-signed certificates.
-    required: false
+    type: bool
     default: 'yes'
-    choices:
-      - 'yes'
-      - 'no'
   color:
     description:
       - Allow text to use default colors - use the default of 'normal' to not send a custom color bar at the start of the message
-    required: false
     default: 'normal'
     choices:
       - 'normal'
@@ -100,8 +86,6 @@ options:
   attachments:
     description:
       - Define a list of attachments.
-    required: false
-    default: None
 """
 
 EXAMPLES = """