Add instructions for using with Vim (issue #11)

README.rst

@@ -105,6 +105,15 @@ See Mads Jensen's Scala TextMate bundle:
 
 Reformat using Ctrl-Shift-H.
 
+Use with Vim
+------------
+
+While there is no specific Vim integration at present, you can use
+Scalariform as an external formatter for the ``gq`` command by adding
+the following to ``.vimrc`` ::
+
+  au BufEnter *.scala setl formatprg=scala\ -cp\ /path/to/scalariform_2.8.0-0.0.8.jar\ scalariform.commandline.Main
+
 Command line tool
 -----------------