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/cloud/rackspace/rax_network.py

@@ -29,11 +29,9 @@ options:
   label:
     description:
      - Label (name) to give the network
-    default: null
   cidr:
     description:
      - cidr of the network being created
-    default: null
 author:
     - "Christopher H. Laco (@claco)"
     - "Jesse Keating (@j2sol)"