CUG: recommend Rose under storage and discovery (etc.).

Recommend use of Rose with cylc under the *Suite Storage, Discovery, Revision Control, and Deployment* section in the cylc user guide.

@dpmatthews and @matthewrmshin - I have essentially just linked to Rose documentation after giving a short and non-specific plug for Rose.  If you would like more than that I'm happy to do it - but please provide some suggested text.