Add justification and some further reading on using a leading semi colon before an IIFE to the Semicolons section.

README.md

@@ -907,13 +907,15 @@
       return name;
     })();
 
-    // good
+    // good (guards against the function becoming an argument when two files with IIFEs are concatenated)
     ;(function() {
       var name = 'Skywalker';
       return name;
     })();
     ```
 
+    [Read more](http://stackoverflow.com/a/7365214/1712802).
+
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