Apollo Client version mismatch

On the client tutorial section #5

**Set up your development environment**
The source code for client uses apollo-client v2.5.1 while the tutorial is referring to version 3 alpha

https://www.apollographql.com/docs/tutorial/client.html#dev-environment

Open the linked client tutorial at section #5 and compare the Apollo Client version described there with the version used by the client source. Determine which version the tutorial should consistently reference, then update the relevant tutorial or source reference. Done means the tutorial and client code no longer describe mismatched versions.

Written by the indexing model from the issue text.