work on path

Work on SkPath.h documentation; fixed self-consistency
bugs identified by bookmaker. Fixed a couple of
minor typos in SkPath.h itself.

Also brought SkPaint and SkCanvas docs up to date.

TBR=reed@google.com
Docs-Preview: https://skia.org/?cl=39040
Bug: skia: 6898
Change-Id: Id89d4e2fa7fb6ee2e3cbec7ea762e06308b67d8b
Reviewed-on: https://skia-review.googlesource.com/39040
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@skia.org>
12 files changed