Add chdir for prepare-docs-for-afs
Add chdir for prepare-docs-for-afs

We need to be running out shell commands within the proper git src.

Change-Id: I9bb6bb85b1fc68cd475eddef38ed6bd11ee0f9dc
Signed-off-by: Paul Belanger <e7139c8e6c4ea75cc1c287ce081b2dc0f3ab39ec@redhat.com>

openstack-infra/openstack-zuul-jobs,openstack-infra/openstack-zuul-jobs