Missing documentation for config file

[jfrosch]

In the CLI docs, an option listed is to use a config file, e.g.

-c, --config   <string>  - Path to .upstash.json file

However, I can't find any documentation on the structure of that file.

If there are docs, it would be helpful to link to them in the README. If there are no docs, then it would be helpful if there were some example JSON files or something.