Cleanup monitoring README doc.
Cleanup monitoring README doc.

Just making it more up-to-date with the recent changes.

BUG=None
R=jcgregorio@google.com

Review URL: https://codereview.chromium.org/720693004

google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot