Fix a broken code block for example (#276)

rhysd · Kuniwak · commit 6422c268c190 · 2018-06-18T18:33:02.000+09:00
diff --git a/README.rst b/README.rst
@@ -127,7 +127,7 @@ Comment config
 
 You can enable/disable linting policies by a comment as following:
 
-..
+.. code:: vim
 
     " vint: -ProhibitAbbreviationOption
 
