Extend Apollo Client section in GraphQL dev guide
Problem to solve
Currently, the section about setting Apollo Client in frontend development GraphQL guideline is short and it doesn't describe the following points:
- settings we pass to default client to configure;
- immutability pattern introduced in Apollo Client 2.6 (
assumeImmutableResults
option) - batching HTTP requests;
Proposal
Add more details on Apollo Client in order to help new developers onboard with GraphQL smoothly.