Clarify use case and usage instructions for Entity Reference Entity Modify

Problem/Motivation

I see the submodule "Entity Reference Entity Modify" module and that it 'Stores entity reference entity modifications regardless of referenced type.' Also that it depends on Media Library Media Modify, and not the other way around. But i don't understand what it does!

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes