Add links to documentation

gui/index.html

@@ -665,7 +665,9 @@ span.mainfunction {color: #993300; font-weight: bolder}
 		simply streams data from the I2S hardware to its 4 output ports.</p>
 	<h3>Hardware</h3>
 	<p>See this Sparkfun blog for <a href="https://www.sparkfun.com/news/2055" target="_blank">how
-		to connect two audio adaptors for 4 channel audio</a>.
+		to connect two audio adaptors for 4 channel audio</a>.</p>
+	<p>For Teensy 4 and Rev D audio shields, see
+		<a href="https://forum.pjrc.com/threads/61123?p=242054&viewfull=1#post242054">this forum thread</a>.</p>
 	<p>The I2S signals are used in "master" mode, where Teensy creates
 		all 3 clock signals and controls all data timing.</p>
 	<table class=doc align=center cellpadding=3>
@@ -1510,7 +1512,9 @@ Returns the actual achieved attenuation of the anti-aliasing filter. If the inpu
 	<h3>Hardware</h3>
 	<p>See this Sparkfun blog for <a href="https://www.sparkfun.com/news/2055" target="_blank">how
 		to connect two audio adaptors for 4 channel audio</a>.  More
-		<a href="https://forum.pjrc.com/threads/29373-Bit-bang-multiple-I2S-inputs-simultaneously?p=79606#post79606" target="_blank">details</a> are also available.
+		<a href="https://forum.pjrc.com/threads/29373-Bit-bang-multiple-I2S-inputs-simultaneously?p=79606#post79606" target="_blank">details</a> are also available.</p>
+	<p>For Teensy 4 and Rev D audio shields, see
+		<a href="https://forum.pjrc.com/threads/61123?p=242054&viewfull=1#post242054">this forum thread</a>.</p>
 	<p>The I2S signals are used in "master" mode, where Teensy creates
 		all 3 clock signals and controls all data timing.</p>
 	<table class=doc align=center cellpadding=3>
@@ -2255,7 +2259,8 @@ Returns the actual achieved attenuation of the anti-aliasing filter. If the inpu
 	<p>Audio from
 		master mode TDM may be used in the same project as ADC, DAC and
 		PWM signals, because all remain in sync to Teensy's timing</p>
-	<!--<h3>Examples</h3>-->
+	<h3>Examples</h3>
+	<p><a href="https://www.youtube.com/watch?v=LOnEv4EDYsk">Video Demo</a> (YouTube)
 	<h3>Notes</h3>
 	<p>Only one TDM input and one TDM output object may be used.  The
 		I2S hardware is used by TDM, so TDM objects may not be used