delete color4f pin from docs

TBR=brianosman@google.com
NOTRY=true
Docs-Preview: https://skia.org/?cl=167102
Bug: skia:
Change-Id: Iafd1680f99531a466291680d53b97635af5c8780
Reviewed-on: https://skia-review.googlesource.com/c/167102
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
3 files changed