Pluggable transport docs aren't ending up in the windows bundles.

Pluggable transport docs (the Obfsproxy, FlashProxy, and fteproxy directories) aren't ending up in pluggable-transports-win32-gbuilt.zip. Here is an untested patch to do it.

Incidentally, the linux descriptor doesn't refer to the Data/ directory and the windows one does. Maybe Data/ was meant to be Docs/ in the windows descriptor all along, and Data/ should be removed as well.