Add example of yaml file with --extra-vars (#79521)

docs/docsite/rst/playbook_guide/playbooks_variables.rst

@@ -331,14 +331,16 @@ When passing variables with ``--extra-vars``, you must escape quotes and other s
     ansible-playbook arcade.yml --extra-vars '{"name":"Conan O'\\\''Brien"}'
     ansible-playbook script.yml --extra-vars "{\"dialog\":\"He said \\\"I just can\'t get enough of those single and double-quotes"\!"\\\"\"}"
 
-If you have a lot of special characters, use a JSON or YAML file containing the variable definitions.
 
 vars from a JSON or YAML file
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+If you have a lot of special characters, use a JSON or YAML file containing the variable definitions. Prepend both JSON and YAML filenames with `@`.
+
 .. code-block:: text
 
     ansible-playbook release.yml --extra-vars "@some_file.json"
+    ansible-playbook release.yml --extra-vars "@some_file.yaml"
 
 
 .. _ansible_variable_precedence: