doc: Add details on qemu glusterfs integration

Change-Id: Ib3cd71f278c29483a467ee5afdd1aeb9e5f54547
BUG: 1086783
Signed-off-by: Bharata B Rao <bharata.rao@gmail.com>
Signed-off-by: Humble Chirammal <hchiramm@redhat.com>
Signed-off-by: Satheesaran S <satheesaran@gmail.com>
Reviewed-on: http://review.gluster.org/7834
Reviewed-by: Lalatendu Mohanty <lmohanty@redhat.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Niels de Vos <ndevos@redhat.com>