message: doc: add `**Note**:` to make quote block like a note
diff: @@ -100,7 +100,8 @@ parallel, reporting the success and failure of each test. See [the `harness`
  field](#the-harness-field) if you want to use a different harness or test
  strategy.
  -> There is another style of test in Cargo: [documentation tests][documentation examples].
  +> **Note**: There is another special style of test in Cargo:
  +> [documentation tests][documentation examples].
  > They are handled by `rustdoc` and have a slightly different execution model.
  > For more information, please see [`cargo test`][cargo-test-documentation-tests].
  