Go Documentation Update for Travel Sample for Couchbase 4.5 Features

In support of the application update, update the documentation with the new tutorial following the pattern from DOC-1734.

This update could either be two documents, one conceptual and one a series of steps or it could be a set of included content and a single document per SDK. Either way, it should have the content more step oriented than the current docs and should be specific to the SDK.