rename example config file

doc/default.cfg.example → doc/example.cfg

@@ -103,6 +103,7 @@ set world.game.mob.spawn.natural true
 set world.game.environment.footprints true
 set world.game.environment.fire.spread false
 set world.game.environment.time.speed 96
+set world.game.environment.season auto
 set world.game.motd NULL
 set world.map.type default
 set world.server.chunk.range.active 2