Ends project gating for doc8
Ends project gating for doc8

Remove doc8 from the gate as the project has been migrated to PyCQA [1].

[1] http://lists.openstack.org/pipermail/openstack-discuss/2019-July/007878.html

Change-Id: I740c66cd959db1efa8ca8c9f29d4da4b66fbd993
Signed-off-by: Stephen Finucane <492121341a95b3c3aab646bed44634f739dd019b@redhat.com>

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