Docs: Add Section on Custom Queries from Custom Operations

[thekevinbrown]

Describe the bug

There currently is no section in the docs on how to query your data providers. We explain how to add custom operations, but not what to do from there.

Expected behavior
Docs should show examples of how to do this.

Actual behavior
Docs lack examples of how to do this.

Additional context
https://graphweaver.slack.com/archives/D0730MYM74Z/p1726103546839589?thread_ts=1723672001.215299&cid=D0730MYM74Z