Add swift to dsvm doc/unit-test skip
Add swift to dsvm doc/unit-test skip

I noticed in Iddd27cb54f1d9f062b9c47ff9ad6a2bef3650d6b that we're
running gate-swift-dsvm-functional-nv for a devstack documentation
change.

Add this to the skip list, and also update the comment a bit

Change-Id: I770f2cd1cf4ff73641c78061537a83502635fc25

dongwenjuan/project-config,coolsvap/project-config,noorul/os-project-config,openstack-infra/project-config,Tesora/tesora-project-config,openstack-infra/project-config,noorul/os-project-config,coolsvap/project-config,dongwenjuan/project-config,Tesora/tesora-project-config