Document the need to rename .js files to .ng

[ccortezia]

I believe the need to rename is intentional, probably to avoid any conflict with the meteor default build chain. That said, some documentation would be nice, since it took me some digging and experimentation time until I could deploy a production build.

Anyway, thanks for the trouble of packaging this for the community.

[JNissi]

Thanks for reporting. Nice to hear someone else finds this useful.