Panos/doc fragment (#37696)

* Create PanOS module documentation fragment

- Module documentation fragment currently holds 3 parameters
- It most likely won't be used in every single module since there is
some variance

* Modified PanOS module for use doc_frags

- Where documentation is consistent, module documentation now uses a
documentation fragment instead of all documentation being contained in
the module.

* Formatting and syntax error fixes

Updated some formatting errors to make ansibot happy.

* Revisions for grammar

lib/ansible/modules/network/panos/panos_pg.py

@@ -30,18 +30,6 @@ version_added: "2.3"
 requirements:
     - pan-python
 options:
-    ip_address:
-        description:
-            - IP address (or hostname) of PAN-OS device
-        required: true
-    password:
-        description:
-            - password for authentication
-        required: true
-    username:
-        description:
-            - username for authentication
-        default: "admin"
     pg_name:
         description:
             - name of the security profile group
@@ -72,6 +60,7 @@ options:
             - commit if changed
         type: bool
         default: 'yes'
+extends_documentation_fragment: panos
 '''
 
 EXAMPLES = '''