JS: Add change note in new format

Author: asgerf

javascript/change-notes/2020-11-06-date-functions.md

@@ -0,0 +1,7 @@
+lgtm,codescanning
+* The security queries now track taint through the format string of a date-formatting operation.
+  Affected packages are
+    [moment](https://npmjs.com/package/moment),
+    [moment-timezone](https://npmjs.com/package/moment-timezone),
+    [date-fns](https://npmjs.com/package/date-fns), and
+    [dateformat](https://npmjs.com/package/dateformat).