Added Descope as Provider

[gaokevin1]

What kind of change does this PR introduce?

This PR adds 'descope' to the Provider type. Descope as a Provider is also pending being added to supabase/gotrue through this PR and the documentation is handled in this PR

What is the current behavior?

There is a type error because there is no 'descope' in Provider type.

What is the new behavior?

Remove the type error in the IDE.

Additional context