update readme files (kcp_mtu parts)

Author: cnbatch

README.md

@@ -168,7 +168,7 @@ encryption_algorithm=AES-GCM
 | mux_tunnels  | 0 - 65535 |否 | 预设值为 0，等于不使用多路复用通道<br>该选项是指两个KCP端之间的多路复用通道数<br>仅限客户端启用|
 | stun_server  | STUN 服务器地址 |否|listen_port 为端口范围模式时不可使用|
 | log_path  | 存放 Log 的目录 |否|不能指向文件本身|
-| kcp_mtu  | 正整数 |否|预设值1440|
+| kcp_mtu  | 正整数 |否|预设值1440。调用 ikcp_setmtu() 设置的值，亦即 UDP 数据包内数据内容的长度|
 | kcp  | manual<br>fast1 - 6<br>regular1 - 5<br> &nbsp; |是|手动设置<br>快速<br>常速<br>(末尾数字：数值越小，速度越快)|
 | kcp_sndwnd  | 正整数 |否|预设值见下表，可以单独覆盖|
 | kcp_rcvwnd  | 正整数 |否|预设值见下表，可以单独覆盖|

README_EN.md

@@ -168,7 +168,7 @@ encryption_algorithm=AES-GCM
 | mux_tunnels  | 0 - 65535 |No | The default value is 0, which means that multiplexing is disabled. This option means how many multiplexing tunnels between two KCP endpoints.<br>Client Mode only.|
 | stun_server  | STUN Server's address |No| Cannot be used if listen_port option is port range mode|
 | log_path  | The directory where the Logs are stored |No|Cannot point to the file itself|
-| kcp_mtu  | Positive Integer |No|Default value is 1440|
+| kcp_mtu  | Positive Integer |No|This option refers to the length of the data content within a UDP packet. <br>The value set for this option refers to the value set by calling ikcp_setmtu(). <br>Default value is 1440.|
 | kcp  | manual<br>fast1 - 6<br>regular1 - 5<br> &nbsp; |Yes|Setup Manually<br>Fast Modes<br>Regular Speeds<br>(the number at the end: the smaller the value, the faster the speed)|
 | kcp_sndwnd  | Positive Integer |No|See the table below for default values, which can be overridden individually|
 | kcp_rcvwnd  | Positive Integer |No|See the table below for default values, which can be overridden individually|

docs/parameters_en.md

@@ -15,7 +15,8 @@
 | mux_tunnels  | 0 - 65535 |No | The default value is 0, which means that multiplexing is disabled. This option means how many multiplexing tunnels between two KCP endpoints.<br>Client Mode only.|
 | stun_server  | STUN Server's address |No| Cannot be used if listen_port option is port range mode|
 | log_path  | The directory where the Logs are stored |No|Cannot point to the file itself|
-| kcp_mtu  | Positive Integer |No|Default value is 1440|
+| mtu  | Positive Integer |No|Default value is 1440|
+| kcp_mtu  | Positive Integer |No|This option refers to the length of the data content within a UDP packet. <br>The value set for this option refers to the value set by calling ikcp_setmtu(). <br>Default value is 1440.|
 | kcp  | manual<br>fast1 - 6<br>regular1 - 5<br> &nbsp; |Yes|Setup Manually<br>Fast Modes<br>Regular Speeds<br>(the number at the end: the smaller the value, the faster the speed)|
 | kcp_sndwnd  | Positive Integer |No|See the table below for default values, which can be overridden individually|
 | kcp_rcvwnd  | Positive Integer |No|See the table below for default values, which can be overridden individually|

docs/parameters_zh-hans.md

@@ -15,7 +15,7 @@
 | mux_tunnels  | 0 - 65535 |否 | 预设值为 0，等于不使用多路复用通道<br>该选项是指两个KCP端之间的多路复用通道数<br>仅限客户端启用|
 | stun_server  | STUN 服务器地址 |否|listen_port 为端口范围模式时不可使用|
 | log_path  | 存放 Log 的目录 |否|不能指向文件本身|
-| kcp_mtu  | 正整数 |否|预设值1440|
+| kcp_mtu  | 正整数 |否|预设值1440。调用 ikcp_setmtu() 设置的值，亦即 UDP 数据包内数据内容的长度|
 | kcp  | manual<br>fast1 - 6<br>regular1 - 5<br> &nbsp; |是|手动设置<br>快速<br>常速<br>(末尾数字：数值越小，速度越快)|
 | kcp_sndwnd  | 正整数 |否|预设值见下表，可以单独覆盖|
 | kcp_rcvwnd  | 正整数 |否|预设值见下表，可以单独覆盖|