TRANSFORM_INVALID_GROUP_CHARS: document "ignore" option (#57318)

Co-Authored-By: Alicia Cozine <879121+acozine@users.noreply.github.com>

changelogs/fragments/group-chars-ignore-doc.yaml

@@ -0,0 +1,3 @@
+---
+bugfixes:
+- documented ``ignore`` option for ``TRANSFORM_INVALID_GROUP_CHARS``

lib/ansible/config/base.yml

@@ -1421,13 +1421,14 @@ TRANSFORM_INVALID_GROUP_CHARS:
   description:
     - Make ansible transform invalid characters in group names supplied by inventory sources.
     - If 'never' it will allow for the group name but warn about the issue.
+    - When 'ignore', it does the same as 'never', without issuing a warning.
     - When 'always' it will replace any invalid charachters with '_' (underscore) and warn the user
-    - When 'silently', it does the same as 'always' sans the warnings.
+    - When 'silently', it does the same as 'always', without issuing a warning.
   env: [{name: ANSIBLE_TRANSFORM_INVALID_GROUP_CHARS}]
   ini:
   - {key: force_valid_group_names, section: defaults}
   type: string
-  choices: ['always', 'never', 'silently']
+  choices: ['always', 'never', 'ignore', 'silently']
   version_added: '2.8'
 INVALID_TASK_ATTRIBUTE_FAILED:
   name: Controls whether invalid attributes for a task result in errors instead of warnings