[gold] Sketch out beginnings of PROD.md
[gold] Sketch out beginnings of PROD.md

Bug: skia:
Change-Id: Ia983ccf881dd53389fbbd4d68fe68c00d32c812e
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/204767
Commit-Queue: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Reviewed-by: Stephan Altmueller <43343ec95731c0e8daa7359daf7f2f3935582b24@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot