Add ICAR to the list of distributions in the docs

[daniel-saunders-phil]

I added a new distribution in #6831 but it's not appearing on the API reference on the website. I'm pretty sure I just need to change the .rst file in the docs folder.

---

📚 Documentation preview 📚: https://pymc--6867.org.readthedocs.build/en/6867/

[daniel-saunders-phil]

Doesn't seem to be working but I'm at a loss for what else needs to be fixed. I checked recent merged PRs on other distributions and only saw them modifying the .rst files. Could it be related to releases? The ICAR distribution just got added and it hasn't been put into a release yet. So maybe the docs preview is taking the last release + only this PR rather than all recent PRs.

[daniel-saunders-phil]

Hi @OriolAbril is this something you would know about? I spoke with Chris earlier today and we thought maybe it was a rebasing problem because the ICAR distribution and this .rst file weren't on the same branch. Now they are sync'ed up. Yet the docs preview still isn't showing ICAR as an option. If you have any ideas, I would love to hear them.

[OriolAbril]

I see it in the preview: https://pymcio--6867.org.readthedocs.build/projects/docs/en/6867/api/distributions/generated/pymc.ICAR.html. Maybe it was a cache issue? (I have no idea how browsers work)