Audio: Add note about microphones and applause

chapters/audio-touchmix.tex

@@ -13,6 +13,7 @@
 			\item Mute unused microphones (bottom row)
 			\item Adjust hall loudness with rightmost fader
 			\item Adjust individual microphone level with fader or redude "trim" knob when it's clipping
+			\item Please keep microphones un-muted during applause
 		\end{itemize}
 	\end{columns}
 \end{frame}