How does `count(%)` work?

[kyo2bay]

When I read Change to count(*) in Dimensional Metrics Queries I wasn't sure what count(%) refers to.
I assume that count(%) behaves the same way that count(*) will behave after June 9th, 2025,
but it would be helpful if this could be clarified in the document.

[github-actions]

Hi @kyo2bay 👋

Thank you for filing an issue! We'll triage your issue and let you know if we have questions, and then route it to the appropriate team so we can get it solved.