doc: changelog consumer library

Change-Id: I1e641e1a61b78c84ed610a56eabdad1075865cd3
BUG: 1086758
Signed-off-by: Venky Shankar <vshankar@redhat.com>
Reviewed-on: http://review.gluster.org/7856
Reviewed-by: Humble Devassy Chirammal <humble.devassy@gmail.com>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Niels de Vos <ndevos@redhat.com>
Reviewed-on: http://review.gluster.org/7863