Append .git submodule repositories, update guide

Append .git submodule repositories, update guide

The submodule path hierarchy needs to support a name used as
hierarchy for lower level repositories or groupIDs AND allow
for a repository at each level eg submodules/appc and
submodules/appc/deployment are both repos. When viewed
in the submodule directory structure in the doc project, a
repository will have .git appended. The above example would
be submodules/appc.git submodules/appc/deployment.git

Change how to guide and convert existing submodule names
Rebased prior change

Change-Id: Ie16b8bbda7562aaaee3c21eb504dc6e293c98cbd
Issue-ID: DOC-33
Signed-off-by: Rich Bennett <rb2745@att.com>