Document code of the entity management forms

[ilovan]

Provide in-code and readme comprehensive documentation of the entity management code, targeted at any potential new adopters and future maintainers of the current installation.

[lucaju]

@ilovan this repo is very old and overly complicated to the task it is doing. It was a good solution at the time, but it is time to redo it. I believe @ajmacdonald agreed with me on this a few months ago. propose to skip documentation and add this to the redesign process.