Add basic documentation for Field Widget Action submodule

I added a comment - the general documentation should just be about Field Widget Actions, not Field Widget Actions with Automators. It should be described that the module doesn't do anything on its own, but needs processors and then sub pages for different processors.

Thanks, but this was a little to much AI slop and its hallucinating a lot :) The source material it is basing off is just to bad and all over the place.

I'll assign this to Artem if he has time or I'll do it myself, so that we get it properly documented once and for all so you do not have to guess what its doing or go through the whole code base.

Yep, sloppy and lazy… sorry for wasting your time with that. A useful experiment though.

So here's a complete rewrite, high level & low tech, based on my recent experience. Let me know if it goes in the right direction.