Update MessageBird verification Docs

# Improve documentation ## Link https://supabase.com/docs/guides/auth/phone-login ## Describe the problem We from Bird (MessageBird) have updated our products. Your customers are still coming to us for the outdated MessageBird Integration ## Describe the improvement If it helps, we've updated the information on your GitHub; your team just needs to implement the updated version. This will ensure your customers no longer run into the issues they are experiencing at the moment. https://github.com/supabase/auth/pull/2684 https://github.com/supabase/auth/pull/2685 ## Additional context n/a