Clarify scope items are additive in docs and UI
## Problem/motivation
Follow-up to:
#3586195
Scope subscriptions are additive. If you subscribe to use case = "working with text" and tag = "campaign", you will get context items that are scoped to either of these. Meaning, the context item doesn't need *both* of them to be relevant.
## Solution
- Review existing docs and update as needed
- Review UI text and consider clarifying this to the user
issue