Fix badly formatted release note

TrivialFix

Change-Id: I4e8903124ff2ea932cd0d2d7937b8a78b3722a72

releasenotes/notes/bug_1564623_change-e286060a27b02f64.yaml

@@ -1,5 +1,4 @@
 ---
 fixes:
-    For a delete snapshot request, if backend reports that
-    snapshot is busy then state of snapshot is changed to
-    'error_deleting'.
+  - For a delete snapshot request, if backend reports that snapshot is busy
+    then the state of snapshot is changed to 'error_deleting'.