API Domain change

[geromegrignon]

Hello!

Due to governance changes, we are now using the realworld.io domain for the RealWorld demo (both client and API).
Requests from conduit.productionready.io are redirected to api.realworld.io, but such a redirection might lead to inconsistent responses.

We encourage domain change for the community.
If this repository is maintained anymore, we'll consider hosting a demo of your implementation in a few weeks with the domain change.

The demo link will be added to the RealWorld documentation.