Document caching integration into Rails framework

The library ships an implementation of the Rails Cache Store interface: lib/active_support/cache/couchbase_store.rb

But the API docs only briefly describes how to configure it in the existing application ActiveSupport/Cache/CouchbaseStore.html.

The SDK documentation need a page that would provide step-by-step tutorial on how to use it.

References:
1. Rails Guides: https://guides.rubyonrails.org/caching_with_rails.html#cache-stores
2. Couchbase Python SDK Caching Tutorial: https://docs.couchbase.com/python-sdk/current/howtos/caching-example.html