Add a table schema API in doc
Add a table schema API in doc

The description of table schema API lacks in docs. This patch adds
the API.

Change-Id: I5d1dbc76b03d4095ceb92c29c88972477f863279

openstack/congress,ramineni/my_congress,ramineni/my_congress,ekcs/congress,ramineni/my_congress,ramineni/my_congress,ekcs/congress,ekcs/congress,ekcs/congress,openstack/congress