Added a warning noticed ot the pgadmin 4 architecture docs

to let users know there are compatibility issues with pgAdmin 4
and pg15

Issue: [sc-16516]

Author: ValClarkson

docs/content/architecture/pgadmin4.md

@@ -20,6 +20,10 @@ immediately have access to your databases.
 
 ## Deploying pgAdmin 4
 
+{{% notice warning %}}
+Unfortunately, pgAdmin 4 is not currently compatible with PostgreSQL 15.
+{{% /notice %}}
+
 If you've done the [quickstart]({{< relref "quickstart/_index.md" >}}), add the
 following fields to the spec and reapply; if you don't have any Postgres clusters
 running, add the fields to a spec, and apply.