subscriptions-transport-ws is not maintained anymore

[diegoglezbahamonde]

[KeithGillette]

Yes, I think think the Apollo Angular documentation should be updated to use the Apollo-recommended graphql-ws WebSockets implementation. We've replaced subscriptions-transport-ws with graphql-ws in our Apollo Angular project following the graphql-ws Apollo Client Web Recipe but are still figuring out how to cleanly unsubscribe from all GraphQL Subscriptions on user sign-out, as graphql-ws doesn't seem to have an equivalent to the subscriptions-transport-ws SubscriptionClient.unsubscribeAll().