[mintlify]

Adds Topic: Read at $0.005 per resource and Space topic_ids expansions to the expansion billing docs, alongside Media, Poll, and Place.

Based on PPU: document expansion billing and a Slack request from Taylor Caldwell.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}