remove SK_MaxSizeT from docs

match review.skia.org/135180

TBR=bungeman@google.com

Docs-Preview: https://skia.org/?cl=135400
Bug: skia:6898
Change-Id: I0fb50045796447b18d040be04b130cb35fdd6bdb
Reviewed-on: https://skia-review.googlesource.com/135400
Commit-Queue: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
3 files changed