Update FAQ with reference to configuration issue #655 (#656)

docs/faq.html

@@ -241,6 +241,11 @@
 					<p>
 						No. This would drastically slow down parsing, as it would require the worker to wait after every chunk for a "continue" signal from the main thread. But you <i>can</i> abort workers by calling <code>.abort()</code> on the parser that gets passed to your callback function.
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+
+					<h6>I set worker:true and now I'm getting an error: "window is not defined." How do I fix it?</h6>
+					<p>
+						This is a fairly common issue with configuration and it appears to be related to the use of React or other third party tools. Since this is a configuration issue, the exact steps needed to solve it may vary. See <a href="https://github.com/mholt/PapaParse/issues/655">Issue #655</a> on GitHub for a solution that worked for one person, and for links to other related issues.
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