corrected required docs as only boolean is allowed

these complex values were not displayed and would always show the fields as requried

lib/ansible/modules/cloud/amazon/ec2_vpc.py

@@ -24,8 +24,8 @@ version_added: "1.4"
 options:
   cidr_block:
     description:
-      - "The cidr block representing the VPC, e.g. 10.0.0.0/16"
-    required: false, unless state=present
+      - "The cidr block representing the VPC, e.g. 10.0.0.0/16", required when I(state) is 'present'.
+    required: false
   instance_tenancy:
     description:
       - "The supported tenancy options for instances launched into the VPC."

lib/ansible/modules/cloud/amazon/elasticache.py

@@ -68,7 +68,7 @@ options:
   cache_subnet_group:
     description:
       - The subnet group name to associate with. Only use if inside a vpc. Required if inside a vpc
-    required: conditional
+    required: false
     default: None
     version_added: "1.7"
   security_group_ids:

lib/ansible/modules/cloud/openstack/os_router.py

@@ -54,8 +54,9 @@ options:
    network:
      description:
         - Unique name or ID of the external gateway network.
+        - required I(interfaces) or I(enable_snat) are provided,
      type: string
-     required: true when I(interfaces) or I(enable_snat) are provided,
+     required: false
                false otherwise.
      default: None
    external_fixed_ips:

lib/ansible/modules/cloud/openstack/os_subnet.py

@@ -42,7 +42,8 @@ options:
    network_name:
      description:
         - Name of the network to which the subnet should be attached
-     required: true when state is 'present'
+        - requried when I(state) is 'present'
+     required: false
    name:
      description:
        - The name of the subnet that should be created. Although Neutron
@@ -52,8 +53,8 @@ options:
    cidr:
      description:
         - The CIDR representation of the subnet that should be assigned to
-          the subnet.
-     required: true when state is 'present'
+          the subnet. Required when I(state) is 'present'
+     required: false
      default: None
    ip_version:
      description:

lib/ansible/modules/cloud/openstack/os_user.py

@@ -41,7 +41,8 @@ options:
    password:
      description:
         - Password for the user
-     required: true when I(state) is present
+        - Required when I(state) is present
+     required: false
      default: None
    email:
      description: