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/nxos/nxos_user.py

@@ -43,15 +43,11 @@ options:
         exclusive with the C(name) argument.
     aliases: ['users', 'collection']
     version_added: "2.4"
-    required: false
-    default: null
   name:
     description:
       - The username to be configured on the remote Cisco Nexus
         device.  This argument accepts a string value and is mutually
         exclusive with the C(aggregate) argument.
-    required: false
-    default: null
   configured_password:
     description:
       - The password to be configured on the network device. The
@@ -66,7 +62,6 @@ options:
         set to C(always), the password will always be updated in the device
         and when set to C(on_create) the password will be updated only if
         the username is created.
-    required: false
     default: always
     choices: ['on_create', 'always']
   role:
@@ -75,23 +70,19 @@ options:
         device running configuration.  The argument accepts a string value
         defining the role name.  This argument does not check if the role
         has been configured on the device.
-    required: false
-    default: null
     aliases: ['roles']
   sshkey:
     description:
       - The C(sshkey) argument defines the SSH public key to configure
         for the username.  This argument accepts a valid SSH key value.
-    required: false
-    default: null
   purge:
     description:
       - The C(purge) argument instructs the module to consider the
         resource definition absolute.  It will remove any previously
         configured usernames on the device with the exception of the
         `admin` user which cannot be deleted per nxos constraints.
-    required: false
-    default: false
+    type: bool
+    default: 'no'
   state:
     description:
       - The C(state) argument configures the state of the username definition
@@ -99,7 +90,6 @@ options:
         to I(present), the username(s) should be configured in the device active
         configuration and when set to I(absent) the username(s) should not be
         in the device active configuration
-    required: false
     default: present
     choices: ['present', 'absent']
 """