Change the local.conf ref
Change the local.conf ref

The README.rst of devstack folder is only for reading. It will
not be converted as html. So remove the download tag, just add
ref for local.conf. Make it more comfort to read from github.

Change-Id: I6c4b5114c1930f14c9c6d9ec6b9cc739462fc913

openstack/searchlight,openstack/searchlight,openstack/searchlight