Updated description for /readines endpoint

Author: tisnik

src/app/endpoints/health.py

@@ -127,6 +127,14 @@ async def readiness_probe_get_method(
     - response: The outgoing HTTP response (used by middleware).
     - auth: Authentication tuple from the auth dependency (used by middleware).
 
+    ### Raises:
+    - HTTPException: with status 401 for unauthorized access.
+    - HTTPException: with status 403 if permission is denied.
+    - HTTPException: with status 500 and a detail object containing `response`
+      and `cause` when service configuration is wrong or incomplete.
+    - HTTPException: with status 503 and a detail object containing `response`
+      and `cause` when unable to connect to Llama Stack.
+
     ### Returns:
     - ReadinessResponse: Object with `ready` indicating overall readiness,
       `reason` explaining the outcome, and `providers` containing the list of