Add Garrison README

Added a Garrison README with a line about Garrison no longer
being a supported machine. This can up updated in the future
if Garrison becomes supported again.

Change-Id: Ib3040500ed8b634b1fb0f5ce1b3156f7885d49aa
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
1 file changed