Remove errant commas in documentation.
Remove errant commas in documentation.

A simple fix but helpful when you're getting started.
nevesenin/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,xuorig/graphql-ruby,rmosolgo/graphql-ruby,xuorig/graphql-ruby,nevesenin/graphql-ruby,xuorig/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,rmosolgo/graphql-ruby