Tweak some markup

Author: bbatsov

doc/modules/ROOT/pages/contributing/hacking.adoc

@@ -80,8 +80,8 @@ Run all tests with:
 
  $ make test
 
-(Note: tests may not run correctly inside Emacs' `shell-mode` buffers. Running
-them in a terminal is recommended.)
+NOTE: Tests may not run correctly inside Emacs' `shell-mode` buffers. Running
+them in a terminal is recommended.
 
 You can also check for compliance with a variety of coding standards in batch mode (including docstrings and byte-compilation warnings):