minor docs example fix

minor docs example fix

TBR=reed@google.com
NOTRY=true

Bug: skia:8439
Change-Id: Id40358b8e06c508d777e016dc18a47299bd06e8d
Reviewed-on: https://skia-review.googlesource.com/c/177340
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
1 file changed