docs(event): add missing documentation

Author: theEvilReaper

game/src/main/java/net/onelitefeather/cygnus/event/GameStartEvent.java

@@ -2,5 +2,13 @@
 
 import net.minestom.server.event.Event;
 
+/**
+ * The event will be called when the game starts.
+ *
+ * @author theEvilReaper
+ * @version 1.0.0
+ * @see net.onelitefeather.cygnus.phase.GamePhase
+ * @since 2.3.1
+ */
 public class GameStartEvent implements Event {
 }