Update hooks-README.md

I think letting know to users of Windows that a shebang line is expected at the start of their non bat scripts is a good idea, since its not typical for Windows users to write shebangs. I found out myself not knowing how to make my python and node.js scripts to work as hooks until I read cordova-lib\src\cordova\hooker.js line 77, function extractSheBangInterpreter.