Clean up internal/external split in platform docs.
Clean up internal/external split in platform docs.

PiperOrigin-RevId: 296002457

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