Accept other ios_banner types (#33961)

* Accept other ios_banner types

* Use 2.6-compatible format string

* Doc option values prior to this update

lib/ansible/modules/network/ios/ios_banner.py

@@ -37,11 +37,11 @@ notes:
 options:
   banner:
     description:
-      - Specifies which banner that should be
-        configured on the remote device.
+      - Specifies which banner should be configured on the remote device.
+        In Ansible 2.4 and earlier only I(login) and I(motd) were supported.
     required: true
     default: null
-    choices: ['login', 'motd']
+    choices: ['login', 'motd', 'exec', 'incoming', 'slip-ppp']
   text:
     description:
       - The banner text that should be
@@ -151,7 +151,7 @@ def main():
     """ main entry point for module execution
     """
     argument_spec = dict(
-        banner=dict(required=True, choices=['login', 'motd']),
+        banner=dict(required=True, choices=['login', 'motd', 'exec', 'incoming', 'slip-ppp']),
         text=dict(),
         state=dict(default='present', choices=['present', 'absent'])
     )