Doc typos and formatting

Change-Id: I727681b43c4603471d7e3973a114a75006f70b79
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/540744
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: James Godfrey-Kittle <jamesgk@google.com>
1 file changed