Update fileglob.py (#78887)

Improve documentation for relative file paths

docs/docsite/rst/playbook_guide/playbook_pathing.rst

@@ -14,6 +14,7 @@ Config paths
 
 By default these should be relative to the config file, some are specifically relative to the current working directory or the playbook and should have this noted in their description. Things like ssh keys are left to use the current working directory because it mirrors how the underlying tools would use it.
 
+.. _playbook_task_paths:
 
 Task paths
 ==========

lib/ansible/plugins/lookup/fileglob.py

@@ -18,6 +18,7 @@ DOCUMENTATION = """
         required: True
     notes:
       - Patterns are only supported on files, not directory/paths.
+      - See R(Ansible task paths,playbook_task_paths) to understand how file lookup occurs with paths.
       - Matching is against local system files on the Ansible controller.
         To iterate a list of files on a remote node, use the M(ansible.builtin.find) module.
       - Returns a string list of paths joined by commas, or an empty list if no files match. For a 'true list' pass C(wantlist=True) to the lookup.