Documentation ask: Provide clear instructions on how to add model API keys

[charlieoliver]

It is mentioned in the documentation but no clear instruction is given on how to add API keys.

[DevOps-zhuang]

Yes, we do need to know how to add our API keys, without it, we can't use it at all.

[oscar-edomex]

Yeah, it's not a clear cut experience. I can go to the settings and set the model and provider but no API key dialogue can be kicked off from here.

Either you @Vision in the chat and then it prompts you or you fire the command from the command palette.

Also, feedback beyond "Key is invalid" because it the key doesn't have credits could be clearer. Yes, part of this could be me not fully reading the README. 😅