Use afs_publisher_target for afs-docs

We changed from afs_target to afs_publisher_target.

Change-Id: If0c00ed5754b80fcff7e452cc8103ecfcaed619a
Signed-off-by: Paul Belanger <pabelanger@redhat.com>
diff --git a/.zuul.yaml b/.zuul.yaml
index e077e97..b16e4a8 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -45,5 +45,5 @@
       jobs:
         - publish-openstack-python-docs:
             vars:
-              afs_target: 'infra/zuul'
+              afs_publisher_target: 'infra/zuul'
         - publish-openstack-python-branch-tarball