That is very interesting project, I have never supported/created a repo of any kind, nevertheless I found some links that could be of your interest, take a look at the following:
Another good suggestion would be to look for help of people that is actually experienced in maintaining a repo, like AlexT who has maintained a pretty good repo since the beginning of the Edison/Galileo boards.
Yocto manual is a reference place to start with this, namely this section: http://www.yoctoproject.org/docs/1.7.2/dev-manual/dev-manual.html#using-runtime-package-management
I've also described the process in my repo thread for Galileo, there's no real difference between Edison and Galileo in this regard (as both use Yocto). See here: How to enable the Yocto-provided package management capability