Document all possible errors for each endpoint

Improve documentation


Describe the problem


The API documentation doesn't mention what errors can be returned by each endpoint. For example, The signIn method can return an AuthException with 400 statusCode and either "Email not confirmed" or "Invalid login credentials" as a message for two different errors, but I only discovered these by testing my code, not from reading the documentation. Maybe there are others which I need to know about too. I need to check for these so I can give an appropriate message to users in their own language, so it's no good just displaying the message that supabase returns.

Describe the improvement


Detail in the documentation which errors are raised by each method in the supabase package.