Add a comment about the hosts func

EduNetworkBuilder/IPAddress.cs

@@ -241,6 +241,10 @@ namespace EduNetworkBuilder
             get { return NetworkAddress + ~_mask; }
         }
 
+        /// <summary>
+        /// Return the number of hosts in the subnet.
+        /// </summary>
+        /// <returns></returns>
         public IEnumerable<UInt32> Hosts()
         {
             for (var host = NetworkAddress + 1; host < BroadcastAddress; host++)