[rbe] Add clearer comments for Merge() and makeTree()
[rbe] Add clearer comments for Merge() and makeTree()

Change-Id: I39f275cad084ba500bd40415f288087f7ed1ecfd
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/593580
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Commit-Queue: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@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