Add another air traffic controller example for mediator

src/MediatorPattern/GroundAirTrafficControl/IAirTrafficControlTower.cs

@@ -0,0 +1,19 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+
+namespace MediatorPattern.GroundAirTrafficControl
+{
+    /// <summary>
+    /// Mediator
+    /// </summary>
+    public interface IAirTrafficControlTower
+    {
+
+        Optional<Lane> RequestPermissionToLand(Plane plane);
+
+        bool RequestLaneForMaintainance(MaintainerTeam team, Lane lane);        
+
+    }
+}