Update release notes

Marenz · Marenz · commit afe98af301e1 · 2024-06-20T11:27:48.000+02:00
Signed-off-by: Mathias L. Baumann &lt;mathias.baumann@frequenz.com&gt;
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
@@ -6,7 +6,7 @@
 
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+* An API key for authorization must now be passed to the client.
 
 ## New Features
 
