Fix: correct link to Apollo CLI

Author: EverlastingBugstopper

graphql_client_cli/README.md

@@ -1,6 +1,6 @@
 # GraphQL client CLI
 
-This is still a WIP, the main use for it now is to download the `schema.json` from a GraphQL endpoint, which you can also do with [apollo-codegen](https://github.com/apollographql/apollo-cli).
+This is still a WIP, the main use for it now is to download the `schema.json` from a GraphQL endpoint, which you can also do with [the Apollo CLI](https://github.com/apollographql/apollo-tooling#apollo-clientdownload-schema-output).
 
 ## Install