docs: Add instructions for storing API tokens in shell configuration …

[ahmetbarut]

…files

[jnsahaj]

This is useful, however this relates to the core concept of environment variables

I feel like someone aware of env variables should also know this.

I might add a more concise version of this in the examples, but this is not required in my opinion.

I think an alternative could be to link to env var setup in general so new users can still read it and understand what to do

Thanks for the suggestion!