Update FAQ on Sentry Prevent AI features (#14799)

Clarify the availability of Prevent AI features in the EU region.

<!-- Use this checklist to make sure your PR is ready for merge. You may
delete any sections you don't need. -->

## DESCRIBE YOUR PR
*Tell us what you're changing and why. If your PR **resolves an issue**,
please link it so it closes automatically.*

## IS YOUR CHANGE URGENT?  

Help us prioritize incoming PRs by letting us know when the change needs
to go live.
- [ ] Urgent deadline (GA date, etc.): <!-- ENTER DATE HERE -->
- [ ] Other deadline: <!-- ENTER DATE HERE -->
- [ ] None: Not urgent, can wait up to 1 week+

## SLA

- Teamwork makes the dream work, so please add a reviewer to your PRs.
- Please give the docs team up to 1 week to review your PR unless you've
added an urgent due date to it.
Thanks in advance for your help!

## PRE-MERGE CHECKLIST

*Make sure you've checked the following before merging your changes:*

- [ ] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs (subject matter
experts)
- [ ] PR was reviewed and approved by a member of the [Sentry docs
team](https://github.com/orgs/getsentry/teams/docs)

## LEGAL BOILERPLATE

<!-- Sentry employees and contractors can delete or ignore this section.
-->

Look, I get it. The entity doing business as "Sentry" was incorporated
in the State of Delaware in 2015 as Functional Software, Inc. and is
gonna need some rights from me in order to utilize my contributions in
this here PR. So here's the deal: I retain all rights, title and
interest in and to my contributions, and by keeping this boilerplate
intact I confirm that Sentry can use, modify, copy, and redistribute my
contributions, under Sentry's choice of terms.

## EXTRA RESOURCES

- [Sentry Docs contributor guide](https://docs.sentry.io/contributing/)

Author: Adal3n3

docs/product/ai-in-sentry/sentry-prevent-ai/index.mdx

@@ -53,3 +53,7 @@ Sentry Prevent AI only runs on GitHub. It will run once when a PR is marked `rea
 - **Why aren't `@sentry` commands working?**
 
   Sentry Prevent AI will respond with a message to enable the `Show Generative AI Features` and `Enable PR Review and Test Generation` settings in your [organization settings](https://sentry.io/orgredirect/settings/:orgslug/), if you have not already enabled them. Once enabled, try `@sentry review` or `@sentry generate-test` again to run Sentry Prevent AI.
+
+- **Are Prevent AI features available in the EU region?**
+
+  Not currently, although we're working on it. In the meantime, you can create a new Sentry org and then follow the set up instructions above.