Update comment about nova-cells-v1 job

Nova is moving nova-cells-v1 to its experimental
queue set of jobs so the comment in devstack should
be updated.

Depends-On: https://review.openstack.org/623538

Change-Id: Iefbaa9b809d1426640cbd47a42213f28c9ec5ff3
Related-Bug: #1807407
diff --git a/.zuul.yaml b/.zuul.yaml
index 21d1a97..4f91b5b 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -557,7 +557,7 @@
     # pruned.
     #
     # * nova-cells-v1: maintained by nova for cells v1 (nova-cells service);
-    #    nova gates on this job, it's in experimental for testing cells v1
+    #    it's in experimental here (and in nova) for testing cells v1
     #    changes to devstack w/o gating on it for all devstack changes.
     # * nova-next: maintained by nova for unreleased/undefaulted
     #    things like cellsv2 and placement-api