Granular documentation fix

gui/index.html

 		at altered speed.  The grainLength is specified in milliseconds, up to
 		one third of the memory from begin();
 		</p>
-	<p class=func><span class=keyword>end</span>();</p>
+	<p class=func><span class=keyword>stop</span>();</p>
 	<p class=desc>Stop granual processing.  The input signal is passed to the
 		output without any changes.
 		</p>