[arch design] convert general purpose to RST
[arch design] convert general purpose to RST

Change-Id: I8a3544166b22b9f3fff8736acdcb2f70e2b77798
Implements: blueprint archguide-mitaka-rst

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals