Add oss-fuzz related documentation for the GPU Gardener

Bug: skia:12695
Change-Id: I7ea1b48c4e2d9097d836b39a811bdb0544b7f4a7
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/484998
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
1 file changed