chore: add faq about project addons

apps/docs/pages/guides/platform/org-based-billing.mdx

@@ -315,6 +315,15 @@ If you head over to your [organizations' billing settings](https://supabase.com/
   infrastructure.
 </details>
 
+<details>
+<summary>
+  <i>Where do I change my project addons such as PITR, Compute and Custom Domain?</i>
+</summary>
+
+Head over to your [projects add ons page](https://supabase.com/dashboard/project/_/settings/addons) to change your compute size, Point-In-Time-Recovery or custom domain.
+
+</details>
+
 <details>
 <summary>
   <i>I have additional questions/concerns, how do I get help?</i>