This change renames the first doc link section Getting Started to
Using Heat and makes the content relevant to end users of Heat.
End users author templates, create stacks, and use the heat CLI.
They are not necessarily interested in installing heat from packages or
devstack.
This change breaks out the basic create-stack content into its own page
and links to that from the first Using Heat contents list. The rest of
the getting started content is moved to the Developers section for now,
pending later changes aimed at developers and operators.
Change-Id: I79988e08864c5a87ebc4f8f5a39102d50b26f748
a2d1b7ee38