Add semaphore to publish-tox-docs-releases job
Add semaphore to publish-tox-docs-releases job

This job fails occasionally when we process several release patches at
the same time due to the shared AFS space. This adds a semaphore to
serialize these operations to avoid conflicts since this is a fairly
quick job.

Change-Id: I2c627c38ab87ed4f12fe8ffccd02ad325efe6dcf
Signed-off-by: Sean McGinnis <961eeb09b6d45516665e15b82e013282c4faf575@gmail.com>

openstack-infra/project-config,openstack-infra/project-config