Fixing small mistake in table for "List" docs
Fixing small mistake in table for "List" docs

There was a small issue with the valid/invalid table for "Non-null lists with nullable items". 
An example that should have been _invalid_ was showing up as _valid_
nevesenin/graphql-ruby,rmosolgo/graphql-ruby,nevesenin/graphql-ruby,nevesenin/graphql-ruby,nevesenin/graphql-ruby,rmosolgo/graphql-ruby,rmosolgo/graphql-ruby,rmosolgo/graphql-ruby