add a 5s idle response option

Author: Concedo

index.html

@@ -18176,6 +18176,7 @@
 								<option value="10">10x</option>
 							</select>
 							<select title="Idle Responses Duration" style="padding:1px; height:auto; width: 27px; appearance: none; font-size: 7pt;" class="form-control" id="idle_duration">
+								<option value="5">5s</option>
 								<option value="15">15s</option>
 								<option value="30">30s</option>
 								<option value="60">60s</option>