Add missing dependency on metrics-jmx

metrics-jmx was extracted in its own artifact and is not a part of
metrics-core any more. Add external dependency, and extend the
documentation.

Change-Id: I640041a67562aea5a2ad9a32f2fa804854829713
4 files changed
tree: adf5c1ff4788556f5164a36bef4ba7ea9adf81ad
  1. BUILD
  2. external_plugin_deps.bzl
  3. src/