modify README.md

Author: Konano

README.md

@@ -18,8 +18,8 @@ In Windows, you need to convert `.cpp` and `.txt` from UTF-8 to GBK.
 find ./src -type f -name "*.txt" -exec enca -L none -x GBK {} \;
 find ./src -type f -name "*.cpp" -exec enca -L none -x GBK {} \;
 (win)
-mkdir build
-cd build
+mkdir buildwin
+cd buildwin
 cmake -G"MinGW Makefiles" ..
 make
 make install