Update link to changelog in OS X windowed copy to github

Was still set to svn.gna.org

projectfiles/Xcode/Resources/SDLMain.nib/designable.nib

@@ -542,7 +542,7 @@ cyBMaWNlbnNlLgo
                                         <fragment>
                                             <string key="content">This is meant to be a concise list of player-visible changes (very minor
 changes may be omitted). For a complete list of changes, see the main
-changelog: http://svn.gna.org/viewcvs/*checkout*/wesnoth/trunk/changelog
+changelog: https://github.com/wesnoth/wesnoth-old/blob/master/changelog
 </string>
                                             <attributes>
                                                 <font key="NSFont" metaFont="label"/>