Add release notes for 1.2.0a3
Add release notes for 1.2.0a3

These will appear here:

  http://docs.openstack.org/developer/oslo.config/

Change-Id: I2e9bfcf2358dddc8354456e3afc52b7e11ed3d5c

varunarya10/oslo.config,JioCloud/oslo.config,metacloud/oslo.config,shad7/oslo.config,magic0704/oslo.config,tianshan/oslo.config,citrix-openstack/build-oslo.config,citrix-openstack-build/oslo.config