message: [docs] add command to CONTRIBUTING for lint & fmt
  Adding the full command to check all linting and formatting to the
  contributation guide reduces need to iterate over not following the
  formatting guidelines and should save some headaches for newcomers.
  Closes:
  Approved by: davidiw
diff: @@ -51,7 +51,7 @@ request workflow is as follows:
  3. If you have changed APIs, update the documentation. Make sure the
  documentation builds.
  4. Ensure all tests and lints pass on each and every commit that is part of
  - your pull request.
  + your pull request. `cargo x lint && cargo xfmt && cargo xclippy --all-targets`
  5. If you haven't already, complete the Contributor License Agreement (CLA).
  6. Submit your pull request.
  