fix doc paint hinting examples

Some references to the old hint enum
remained, so switch them over.

This fixes bookmaker nightly.

TBR=reed@google.com
NOTRY=true
Docs-Preview: https://skia.org/?cl=169825
Bug: skia:
Change-Id: I2d13ae85e6e14e3445a03e361a50e91bb3bdedd2
Reviewed-on: https://skia-review.googlesource.com/c/169825
Auto-Submit: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
4 files changed