update README

README.md

@@ -164,9 +164,10 @@ gost -L=tcp://:2222/192.168.1.1:22 -F=...
 #### 本地端口转发(UDP)
 
 ```bash
-gost -L=udp://:5353/192.168.1.1:53 -F=...
+gost -L=udp://:5353/192.168.1.1:53?ttl=60 -F=...
 ```
 将本地UDP端口5353上的数据(通过代理链)转发到192.168.1.1:53上。
+每条转发通道都有超时时间，当超过此时间，且在此时间段内无任何数据交互，则此通道将关闭。可以通过`ttl`参数来设置超时时间，默认值为60秒。
 
 **注:** 转发UDP数据时，如果有代理链，则代理链的末端(最后一个-F参数)必须是gost SOCKS5类型代理。
 

README_en.md

@@ -164,9 +164,10 @@ The data on the local TCP port 2222 is forwarded to 192.168.1.1:22 (through the
 #### Local UDP port forwarding
 
 ```bash
-gost -L=udp://:5353/192.168.1.1:53 -F=...
+gost -L=udp://:5353/192.168.1.1:53?ttl=60 -F=...
 ```
-The data on the local UDP port 5353 is forwarded to 192.168.1.1:53 (through the proxy chain).
+The data on the local UDP port 5353 is forwarded to 192.168.1.1:53 (through the proxy chain). 
+Each forwarding channel has a timeout period. When this time is exceeded and there is no data interaction during this time period, the channel will be closed. The timeout value can be set by the `ttl` parameter. The default value is 60 seconds.
 
 **NOTE:** When forwarding UDP data, if there is a proxy chain, the end of the chain (the last -F parameter) must be gost SOCKS5 proxy.