Documenting (code) is always a good idea. 
Its hard enoug to find and motivate people that have good coding skills, so the last thing you need is for those people to get frustrated while trying to find out where/how they should start.

Transparent, error-free documentation, website and active mailing list are key here!

I dont have coding skills, but if you need someone to help with the documentation as such, i'm willing to help.