Add naming note to styleguide
Add naming note to styleguide

BUG=skia:

Review-Url: https://codereview.chromium.org/2287683002

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