Replace old gotrue docs with redirect

[mraerino]

- Summary

• Builds for /www are failing constantly right now
• www.gotrueapi.com already redirects to the github repo

- Test plan

• Check deploy preview

- Description for the changelog

n/a

- A picture of a cute animal (not mandatory but encouraged)

[keiko713]

I guess it's still failing because there is value set in UI too? https://app.netlify.com/sites/gotrueapi/settings/deploys#build-settings