message: Add `--projects` option Jest CLI Options docs
  With Jest 20 there was new CLI option introduced `--projects`. This PR proposes documentation changes to include this new flag.
diff: @@ -164,6 +164,10 @@ Activates notifications for test results. Good for when you don't want your cons
  Alias: `-o`. Attempts to identify which tests to run based on which files have changed in the current repository. Only works if you're running tests in a git/hg repository at the moment and requires a static dependency graph (ie. no dynamic requires).
  +### `--projects <project1> ... <projectN>`
  +
  +Run tests from one or more projects.
  +
  ### `--runInBand`
  Alias: `-i`. Run all tests serially in the current process, rather than creating a worker pool of child processes that run tests. This can be useful for debugging.
  