Would it be a good idea for the main mod pages to have a section at the bottom reserved for explaining that mod's configuration options?
Maybe have the current default configs uploaded so that users can restore a broken one if need be. The section could also go over individual aspects of the config file, explaining what they do and what can be changed. I know some configs, like GregTech's for example, can be really confusing at first glance without someone telling you what you are looking at. It would also be a good place to mention how config files differ between the various modpacks.
For example with gregtech, something along the lines of this:
This section allows toggling gregtech's compatibility with other mods. It can be enabled to use Buildcraft, Industrialcraft and Universal Electricity power. These are all enabled by default
This section deals with stack sizes and other core features of gregtech.
**The number of items that can be stored in a Digital Chest. The default is 32768.
A and B is enabled in Unleashed but disabled in Unhinged.
A, B and C changes Vanilla mechanics. This can be reverted by toggling X, Y and Z.
You get the picture.
Downsides would be very long page length and it would be a challenge to keep them up to date if the configs ever changed. Perhaps pages dedicated to mods' configs would be a better idea.
This would have been a very valuable resource when I was setting up my modpack when I first started playing. In most places, a good description of the config files is nowhere to be found.