minor comment add wrt #2643

Author: cowtowncoder

Diff for: src/main/java/com/fasterxml/jackson/databind/util/StdDateFormat.java

@@ -487,6 +487,8 @@ protected void _format(TimeZone tz, Locale loc, Date date,
         } else {
             // 24-Jun-2017, tatu: While `Z` would be conveniently short, older specs
             //   mandate use of full `+0000`
+            // 06-Mar-2020, tatu: Actually statement should read "for compatibility reasons"
+            //   and not standards (unless it is wrt RFC-1123). This will change in 3.0 at latest
 //            formatted.append('Z');
             if( _tzSerializedWithColon ) {
                 buffer.append("+00:00");