app_confbridge: Fix ConfbridgeTalking AMI event description.

Thanks to Chris Howard for pointing this out on the wiki.

Change-Id: I18e56de09a70e736b5d04719d45ef29cf0636705

apps/confbridge/confbridge_manager.c

@@ -189,7 +189,7 @@
 	</managerEvent>
 	<managerEvent language="en_US" name="ConfbridgeTalking">
 		<managerEventInstance class="EVENT_FLAG_CALL">
-			<synopsis>Raised when a confbridge participant unmutes.</synopsis>
+			<synopsis>Raised when a confbridge participant begins or ends talking.</synopsis>
 			<syntax>
 				<parameter name="Conference">
 					<para>The name of the Confbridge conference.</para>