Minor memory player documentation update

gui/index.html

@@ -1533,6 +1533,8 @@ span.mainfunction {color: #993300; font-weight: bolder}
 	<h3>Notes</h3>
 	<p><a href="https://forum.pjrc.com/threads/42401-Instructions-or-tutorials-for-using-wav2sketch?p=135069&viewfull=1#post135069">Step by step instructions for wav2sketch</a>
 		running in Terminal on Macintosh.</p>
+	<p><a href="https://www.pjrc.com/teensy/td_libs_AudioPlayMemory.html">Old documentation about wav2sketch</a>
+		is still available, including details about the data format.</p>
 	<p>TODO: supported sample rates: 11.025, 22.05, 44.1</p>
 	<p>TODO: ulaw vs uncompressed encoding</p>
 	<p>Polyphonic playback can be built by creating multiple