Update AudioSynthWaveform documentation

gui/index.html

@@ -1960,7 +1960,8 @@ The actual packets are taken
 <script type="text/x-red" data-help-name="AudioSynthWaveform">
 	<h3>Summary</h3>
 	<div class=tooltipinfo>
-	<p>Create a waveform: sine, sawtooth, square, triangle, pulse or arbitrary.</p>
+	<p>Create a waveform: sine, sawtooth, square, triangle, pulse, random S&H or arbitrary.</p>
+	<p align=center><img src="img/waveforms.png"></p>
 	</div>
 	<h3>Audio Connections</h3>
 	<table class=doc align=center cellpadding=3>