Remove unused file
Remove unused file

doc/common/wadl/security-groups.wadl is not used at all,
remove it.

Change-Id: I34dad19dad4f9c0250bb4878da18572748d2555b

saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,Akasurde/openstack-manuals,Akasurde/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,potsmaster/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,gongysh2004/openstack-manual,gongysh2004/openstack-manual,saeki-masaki/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,potsmaster/openstack-manuals,kairoaraujo/openstack-manuals,kairoaraujo/openstack-manuals,openstack/openstack-manuals