Correct the client-id fallback in the 0.2.0 notes

Author: chrisuthe

docs/release-notes/0.2.0.md

@@ -22,7 +22,8 @@
 ### Fixed issues
 
 - **The systemd unit now allows `AF_NETLINK`,** so the MAC-derived client id is detected
-  under the shipped hardening rather than falling back to a random id. (#53)
+  under the shipped hardening. Without it `getifaddrs()` fails and the player greets with an
+  empty `client_id`, which a server such as Music Assistant refuses. (#53)
 
 ### Under the hood