add SkDebugCanvas to undocumented

SkDumpCanvas was replaced by SkDebugCanvas as an undefined reference,
but SkDumpCanvas was not added to undocumented.bmh and caused bookmaker
to generate a broken version of site/user/api/SkCanva_Reference.md

The Skia-Commit-Bot detected that the SkCanvas_Reference.md was
changed, and checked it in, causing the online version of SkCanvas
like https://skia.org/user/api/SkCanvas_Reference#SkCanvas_readPixels
to be truncated.

I assume there is a mistake in bookmaker where it wrote an error
to stdout but failed to abort the tool when the *.md file was partially
written. I'll look into that.

This CL adds SkDebugCanvas to undocumented.bmh to fix the documentation.

TBR=brianosman@google.com,rmistry@google.com

Docs-Preview: https://skia.org/?cl=113700
Bug: skia:6898
Change-Id: Ib4e32eea3e56c178d0016f8ae392e28aab5ffafa
Reviewed-on: https://skia-review.googlesource.com/113700
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>

0 files changed, 0 insertions, 0 deletions