[skip ci] Drop make instructions for windows

Windows does not use make. It doesn't make sense to mention a single Windows step, as building on Windows is much more complicated.

Author: iluuu1994

README.md

@@ -82,12 +82,6 @@ Configure your build. `--enable-debug` is recommended for development, see
 
 Build PHP. To speed up the build, specify the maximum number of jobs using `-j` argument:
 
-On Windows:
-```shell
-make -j4
-```
-
-On Unix system:
 ```shell
 make -j4
 ```