Single-Create Documentation
Single-Create Documentation

Since single-create utilizes the existing objects already documented, I added an
example for the request and response, and indicated to look for more details
in the appropriate object's section.

Change-Id: Icdf7f21867457e22086f9c44ab657f95617bee1a
Closes-Bug: #1551428

openstack/octavia,openstack/octavia,openstack/octavia