Improve documentation on setting key

Authentication is really not the best way of storing the key, just the easiest. If you are working with repos and you don't ignore that configuration, your API Key is stored in the repo which is really bad practice.

Instead people will have to read up on how the Key module works and what to store there. If you need a simple way of setting this up for customers, this module eixst: https://www.drupal.org/project/ai_simple_provider_installer →