Thank you for providing a very useful action.

I would like to see additional documentation about the priority attribute. The documentation that I can find on priority consists of:

priority=<number> priority to manage the order of tags

Some questions that could be clarified by additional documentation:

1. In what context does priority impact ordering of tags? On https://hub.docker.com/? On other container registries? On the API results returned from https://hub.docker.com/v2/?
2. Do smaller priority values result in being first or last in the resulting ordering?