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/sendgrid.py

@@ -37,14 +37,10 @@ options:
     description:
       - username for logging into the SendGrid account.
       - Since 2.2 it is only required if api_key is not supplied.
-    required: false
-    default: null
   password:
     description:
       - password that corresponds to the username
       - Since 2.2 it is only required if api_key is not supplied.
-    required: false
-    default: null
   from_address:
     description:
       - the address in the "from" field for the email
@@ -61,44 +57,32 @@ options:
     description:
       - sendgrid API key to use instead of username/password
     version_added: 2.2
-    required: false
-    default: null
   cc:
     description:
       - a list of email addresses to cc
     version_added: 2.2
-    required: false
-    default: null
   bcc:
     description:
       - a list of email addresses to bcc
     version_added: 2.2
-    required: false
-    default: null
   attachments:
     description:
       - a list of relative or explicit paths of files you want to attach (7MB limit as per SendGrid docs)
     version_added: 2.2
-    required: false
-    default: null
   from_name:
     description:
       - the name you want to appear in the from field, i.e 'John Doe'
     version_added: 2.2
-    required: false
-    default: null
   html_body:
     description:
       - whether the body is html content that should be rendered
     version_added: 2.2
-    required: false
-    default: false
+    type: bool
+    default: 'no'
   headers:
     description:
       - a dict to pass on as headers
     version_added: 2.2
-    required: false
-    default: null
 author: "Matt Makai (@makaimc)"
 '''