Add #openstack-self-healing to gerritbot
Add #openstack-self-healing to gerritbot

We are planning to store use cases and specs in the self-healing-sig
repository.  Also monitor a few HA repositories which are inherently
related to self-healing.

Change-Id: I2f975b436f75e3aea05aee23db35778e7df2099f

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