Protobuf update instructions: update and fix.
Protobuf update instructions: update and fix.

Change-Id: Ia5e381cd79cd516cb419c90927546e2b9b2423cc

aehlig/bazel,dslomov/bazel-windows,dslomov/bazel,davidzchen/bazel,ButterflyNetwork/bazel,davidzchen/bazel,akira-baruah/bazel,cushon/bazel,twitter-forks/bazel,davidzchen/bazel,cushon/bazel,katre/bazel,cushon/bazel,safarmer/bazel,akira-baruah/bazel,perezd/bazel,ulfjack/bazel,bazelbuild/bazel,meteorcloudy/bazel,safarmer/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,perezd/bazel,werkt/bazel,dslomov/bazel,cushon/bazel,dslomov/bazel,ButterflyNetwork/bazel,twitter-forks/bazel,davidzchen/bazel,safarmer/bazel,davidzchen/bazel,safarmer/bazel,bazelbuild/bazel,ulfjack/bazel,dslomov/bazel-windows,aehlig/bazel,dslomov/bazel-windows,dslomov/bazel,meteorcloudy/bazel,davidzchen/bazel,akira-baruah/bazel,aehlig/bazel,aehlig/bazel,ulfjack/bazel,davidzchen/bazel,bazelbuild/bazel,twitter-forks/bazel,cushon/bazel,katre/bazel,safarmer/bazel,perezd/bazel,katre/bazel,twitter-forks/bazel,akira-baruah/bazel,dslomov/bazel-windows,twitter-forks/bazel,bazelbuild/bazel,werkt/bazel,dslomov/bazel-windows,aehlig/bazel,katre/bazel,werkt/bazel,werkt/bazel,perezd/bazel,dslomov/bazel,bazelbuild/bazel,ButterflyNetwork/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,perezd/bazel,twitter-forks/bazel,katre/bazel,akira-baruah/bazel,meteorcloudy/bazel,twitter-forks/bazel,ulfjack/bazel,dslomov/bazel,akira-baruah/bazel,bazelbuild/bazel,aehlig/bazel,perezd/bazel,dslomov/bazel-windows,ulfjack/bazel,perezd/bazel,ulfjack/bazel,dslomov/bazel,werkt/bazel,katre/bazel,safarmer/bazel,ulfjack/bazel,aehlig/bazel,meteorcloudy/bazel,ButterflyNetwork/bazel,werkt/bazel,meteorcloudy/bazel,cushon/bazel