doc: update release notes with getaddressinfo label deprecation

doc/release-notes-17578.md

@@ -1,8 +1,13 @@
 Deprecated or removed RPCs
 --------------------------
 
-- The `getaddressinfo` RPC `labels` field now returns an array of label name
-  strings. Previously, it returned an array of JSON objects containing `name` and
-  `purpose` key/value pairs, which is now deprecated and will be removed in
-  0.21. To re-enable the previous behavior, launch with
-  `-deprecatedrpc=labelspurpose`.
+- RPC `getaddressinfo` changes:
+
+  - the `label` field has been deprecated in favor of the `labels` field and
+    will be removed in 0.21. It can be re-enabled in the interim by launching
+    with `-deprecatedrpc=label`.
+
+  - the `labels` behavior of returning an array of JSON objects containing name
+    and purpose key/value pairs has been deprecated in favor of an array of
+    label names and will be removed in 0.21. The previous behavior can be
+    re-enabled in the interim by launching with `-deprecatedrpc=labelspurpose`.