Hello @atBeSa I humbly apologize for the suboptimal experience that you had in going through the tutorials. This should be a fun and rewarding experience.
I pushed up a new version of dgraph/dgraph:standalone:v21.03.0 and dgraph/dgraph:standalone:latest that includes the Ratel binary, so this should now work with the existing documentation.
PS - I forgot to mention this. But you will likely need to purge existing Docker images, as they will undoubtedly be cached, and pull down the images again.
cc: @chewxy @MichelDiz I will follow up later with refactoring build pipeline to support ratel in standalone
cc: @docs docs should now work as is now that ratel is back.