Update android_guide.md

doc/android_guide.md

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 # How to run udp2raw on a rooted android device(arm cpu)
 
-There is currently no GUI for udp2raw on android.Make sure you have installed Terminal to run it.You device has to be rooted,otherwise you cant use raw socket.
+There is currently no GUI for udp2raw on android.Make sure you have installed Terminal to run it.Your device has to be rooted,otherwise you cant use raw socket.
 
 Download udp2raw_arm from https://github.com/wangyu-/udp2raw-tunnel/releases.