[perf] Update format and ingestion docs.
[perf] Update format and ingestion docs.

Bug: skia:
Change-Id: I36952fd0fb16acbc8b9342fef3b0b2bce71046bb
Reviewed-on: https://skia-review.googlesource.com/149224
Reviewed-by: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>
Commit-Queue: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@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