Add gitaly production setup documentation
Gitaly is quite cpu heavy if doing multiple write operations at a time. If we take a look at the project creation path. The gitaly chart can process about 30 project creations per minute. But when doing this, even at a concurrency as low as 2, approximately 2-3 cpu units are needed. (I was able to get to a concurrency of 5 on a 4 cpu unit node but beyond that the creations started timing out)
If more concurrency than than is needed, users will need to ensure gitaly is running on large cpu nodes. Either in the chart, using nodeAffinity and tolerations perhaps, or outside the chart using external gitaly nodes setup using omnibus.
We should document these production requirements, and ensure setting up the appropriate nodeAffinities and tolerations is possible for the gitaly pods.