Make sure ref docs show how to use snapshots libs

[onobc]

Let's be sure the ref docs getting started section shows/mentions the need to setup snapshot repositories on repo.spring.io (Gradle and Maven) if they want to use the lib w/o building locally.

We can probably borrow docs another project that shows how to consume snapshots.

[onobc]

Example pointing to snapshot repo: https://github.com/cloudfoundry/cf-java-client#dependencies