The existing documentation is full of useful bits for setting up TLS
everywhere and TLS for public-only endpoints. This commit adds an
introduction that attempts to describe the usecases for using TLS.
Additionally, it adds short, concise descriptions of the components
needed in TLS deployments and why they're important.
This is going to be the first of a series of documentation patches
that attempt to refactor the existing TLS/SSL documentation to be more
use-case driven. The goal is to make it easier for readers and TripleO
developers to understand how TLS works in TripleO.
Change-Id: I7eaf8f852eaccf4debd0b5095c2622c53b09de4d
391494e7ae