[docs] Document new "lin-123-g580" Golo naming convention.
[docs] Document new "lin-123-g580" Golo naming convention.

Change-Id: I126bee10ebeb34c024c84e5cd6bc5db950a82029
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/529354
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Commit-Queue: Erik Rose <042ad22d8352d59a3d816dac710aebe65456f16e@google.com>

google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia,google/skia