capture items that fall out of scope

[Geoffrey Blotter]

Using the team playbook ideas, and the default templates for Confluence spaces... how do you suggest I manage recording all of the things that fall "out of scope" for a feature being worked on?  The hierarchy of the space is geared towards releases and projects, but what happens when I have a new "feature" that I'm implementing and we have to cut pieces of it for the MVP?  Where do I track those pieces and where do I define what the "complete" feature looks like, as I iterate and release it in phases?

Open to suggestions, Thanks!