Fix broken development version link in README
Fix broken development version link in README

Change-Id: Id9035c167d397cdad32d418c37108586344d8edc

rcherrueau/sqlalchemy-migrate,andras-tim/sqlalchemy-migrate,stackforge/sqlalchemy-migrate,dannon/sqlalchemy-migrate,openstack/sqlalchemy-migrate,openstack/sqlalchemy-migrate,rcherrueau/sqlalchemy-migrate