[gold] Add notes to debug firestore usage
[gold] Add notes to debug firestore usage

Bug: skia:10399
Change-Id: I2d0ac9ab6a16483e3ed7c26736ab3ad7a692ccc8
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/297191
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@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