Fix doc typo.
Fix doc typo.

Added missing quotes.

BUG=angleproject:2297

Change-Id: Ieb6ca4ae37786f48ad3c6f5dccefef25afce23a2
Reviewed-on: https://chromium-review.googlesource.com/852636
Reviewed-by: Yuly Novikov <36f5580f63d0a3eacc17e89a61d11e2f646630d2@chromium.org>
Commit-Queue: Frank Henigman <4f3ccfa167f952ff7263448ff4377acff6a23e5c@chromium.org>

ppy/angle,ppy/angle,ppy/angle,ppy/angle