Merge from Widevine repo of http://go/wvgerrit/49580
This document explains which version of OEMCrypto is compatible with
which version of CE CDM or Android. The intent is to share this on
all Widevine partner repos.
bug: 77637828
Change-Id: Id7db8f9cb5f2a5c6bf35dfecd2ae3b3fabd09c56
testing: documentation only