doc: update README to reflect new exclude mechanism

Signed-off-by: Ingo Müller <[email protected]>

Author: ingomueller-net

README.md

@@ -30,4 +30,9 @@ jobs:
 
 You can pass any other [YAPF parameter](https://github.com/google/yapf#usage) using the `args` setting, e.g. for setting a different code style (default is PEP8), but you can also remove the `with` section entirely if you wish.
 
-If you want to exclude a certain directory, you can use the args field like this: `args: --verbose --exclude '**/tests/**'`. Thank you [@pksol](https://github.com/pksol) for the [example](https://github.com/AlexanderMelde/yapf-action/issues/1).
+If you want to exclude a certain file or directory, you can either use the `--exclude` parameter or a `.yapfignore` file.
+
+### Migration Notice
+Earlier versions of this action did not set the working directory before executing `yapf`.
+
+If you used the `--exclude '**/tests/**'` workaround, you might need to simplify this to `--exclude 'tests/**'` now.