fix param return descriptions

enforce that param and return
descriptions are phrases (begin
with lower case, no trailing
period).

Docs-Preview: https://skia.org/?cl=40767
Bug: skia: 6898
Change-Id: Ib5f2a02441673f71c0780d81c5e4c61200a678e3
Reviewed-on: https://skia-review.googlesource.com/40767
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
12 files changed