Document mosquitto_sub timeout.

ChangeLog.txt

@@ -121,6 +121,8 @@ Client features:
 - Add -c (clean session) to mosquitto_pub.
 - Add --retained-only to mosquitto_sub to exit after receiving all retained
   messages.
+- Add -W to allow mosquitto_sub to stop processing incoming messages after a
+  timeout.
 - Connections now default to using MQTT v3.1.1.
 - Default to using port 8883 when using TLS.
 - mosquitto_sub doesn't continue to keep connecting if CONNACK tells it the

man/mosquitto_sub.1.xml

@@ -50,6 +50,7 @@
 			<arg choice='opt' rep='repeat'><option>-U</option> <replaceable>unsub-topic</replaceable></arg>
 			<arg><option>-v</option></arg>
 			<arg><option>-V</option> <replaceable>protocol-version</replaceable></arg>
+			<arg><option>-W</option> <replaceable>message processing timeout</replaceable></arg>
 			<arg><option>--proxy</option> <replaceable>socks-url</replaceable></arg>
 			<arg><option>--quiet</option></arg>
 			<arg>
@@ -528,6 +529,16 @@
 						Defaults to <option>mqttv311</option>.</para>
 				</listitem>
 			</varlistentry>
+			<varlistentry>
+				<term><option>-W</option></term>
+				<listitem>
+					<para>Provide a timeout as an integer number of seconds.
+						mosquitto_sub will stop processing messages and
+						disconnect after this number of seconds has
+						passed. The timeout starts just after the client has
+						connected to the broker.</para>
+				</listitem>
+			</varlistentry>
 			<varlistentry>
 				<term><option>--will-payload</option></term>
 				<listitem>