doc/protocols: update rtsp options

Define listen_timeout and user_agent. Set timeout and user-agent to deprecated.

Signed-off-by: Andriy Gelman <andriy.gelman@gmail.com>

doc/protocols.texi

@@ -1165,11 +1165,16 @@ Set minimum local UDP port. Default value is 5000.
 Set maximum local UDP port. Default value is 65000.
 
 @item timeout
-Set maximum timeout (in seconds) to wait for incoming connections.
+This option is deprecated. Use @option{listen_timeout} instead. Set maximum timeout (in seconds) to wait for incoming connections.
 
 A value of -1 means infinite (default). This option implies the
 @option{rtsp_flags} set to @samp{listen}.
 
+@item listen_timeout
+Set maximum timeout (in seconds) to establish an initial connection. Setting
+@option{listen_timeout} > 0 sets @option{rtsp_flags} to @samp{listen}. Default is -1
+which means an infinite timeout when @samp{listen} mode is set.
+
 @item reorder_queue_size
 Set number of packets to buffer for handling of reordered packets.
 
@@ -1177,6 +1182,10 @@ Set number of packets to buffer for handling of reordered packets.
 Set socket TCP I/O timeout in microseconds.
 
 @item user-agent
+This option is deprecated. Use @option{user_agent} instead. Override User-Agent header. If not specified, it defaults to the
+libavformat identifier string.
+
+@item user_agent
 Override User-Agent header. If not specified, it defaults to the
 libavformat identifier string.
 @end table