update changelog

Author: corrados

ChangeLog

@@ -22,6 +22,9 @@
   to the text in the chat window?" so that a licence text must now be given in the
   server welcome message (#587, #367, #81)
 
+- added a protocol message for a reduced server list to improve the situation caused
+  by UDP packet fragmentation (#631, #255)
+
 - added translation: Slovak by jose1711 (#635)
 
 - bug fix: crash when using the jam recorder in the server, coded by pljones (#618)