Update build_guide.md

doc/build_guide.md

@@ -73,4 +73,4 @@ cc_cross=/home/wangyu/Desktop/OpenWrt-SDK-15.05-ar71xx-generic_gcc-4.8-linaro_uC
 
 run `make cross`，the just generated `udp2raw_cross` is the binary,compile done. copy it to your router to run.
 
-`make cross` generates non-static binary. If you have any problem on running it,try to compile a static binary by using `make cross2` or `make cross3`.If your toolchain supports static compiling, usually one of them will succeed. The generated file is still named `udp2raw_cross`
+`make cross` generates non-static binary. If you have any problem on running it,try to compile a static binary by using `make cross2` or `make cross3`.If your toolchain supports static compiling, usually one of them will succeed. The generated file is still named `udp2raw_cross`.