Use an always up-to-date codesandbox URL in bug.md (#3844)
Use an always up-to-date codesandbox URL in bug.md (#3844)

* Use an always up-to-date codesandbox URL in bug.md

* Slight sentence adjustment

apollostack/apollo-client,apollostack/apollo-client,apollographql/apollo-client,apollostack/apollo-client,apollographql/apollo-client