README: Modify the note for windows users

Author: mrkn

README.md

@@ -32,9 +32,9 @@ pyenv does not build the shared library in default, so you need to specify `--en
 $ env PYTHON_CONFIGURE_OPTS='--enable-shared' pyenv install 3.7.2
 ```
 
-## Note for Windows
+## Note for Windows users
 
-Currently, pycall.rb does not support Windows.
+Currently, pycall.rb does not support Windows.  Please try to use pycall.rb on WSL2 environment.
 
 On Windows, the error "[BUG] object allocation during garbage collection phase" is occurred at unpredictable timings.