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/amazon/elasticache.py

@@ -32,70 +32,51 @@ options:
   engine:
     description:
       - Name of the cache engine to be used.
-    required: false
     default: memcached
     choices: ['redis', 'memcached']
   cache_engine_version:
     description:
       - The version number of the cache engine
-    required: false
-    default: None
   node_type:
     description:
       - The compute and memory capacity of the nodes in the cache cluster
-    required: false
     default: cache.m1.small
   num_nodes:
     description:
       - The initial number of cache nodes that the cache cluster will have. Required when state=present.
-    required: false
   cache_port:
     description:
       - The port number on which each of the cache nodes will accept connections
-    required: false
-    default: None
   cache_parameter_group:
     description:
       - The name of the cache parameter group to associate with this cache cluster. If this argument is omitted, the default cache parameter group
         for the specified engine will be used.
-    required: false
-    default: None
     version_added: "2.0"
     aliases: [ 'parameter_group' ]
   cache_subnet_group:
     description:
       - The subnet group name to associate with. Only use if inside a vpc. Required if inside a vpc
-    required: false
-    default: None
     version_added: "2.0"
   security_group_ids:
     description:
       - A list of vpc security group names to associate with this cache cluster. Only use if inside a vpc
-    required: false
-    default: None
     version_added: "1.6"
   cache_security_groups:
     description:
       - A list of cache security group names to associate with this cache cluster. Must be an empty list if inside a vpc
-    required: false
-    default: None
   zone:
     description:
       - The EC2 Availability Zone in which the cache cluster will be created
-    required: false
-    default: None
   wait:
     description:
       - Wait for cache cluster result before returning
-    required: false
-    default: yes
-    choices: [ "yes", "no" ]
+    type: bool
+    default: 'yes'
   hard_modify:
     description:
       - Whether to destroy and recreate an existing cache cluster if necessary in order to modify its state
-    required: false
-    default: no
-    choices: [ "yes", "no" ]
+    type: bool
+    default: 'no'
 extends_documentation_fragment:
     - aws
     - ec2