SkQP: Document pre-built APKs

Docs-Preview: https://skia.org/dev/testing/skqp?cl=107027
No-Try: true
Change-Id: I49da6cb21f8165e997be320b946017717f0b618a
Reviewed-on: https://skia-review.googlesource.com/107027
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Stephan Altmueller <stephana@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>
1 file changed