docs: Removing reference to OpenJDK 8

P0 bug, so I'm going to go ahead and submit the fix, *then* run my
test build (so we don't delay in getting the built version). We should
be able to see if I broke something before we push the fix live.

bug: 27597678
Change-Id: I4a13b560ce907832e279db64f5ecf6f3f28e74c2