Updated game board display

Connect4/GameBoard.cs

@@ -130,6 +130,12 @@ public class GameBoard
             for (int column = 0; column < dimensions.Columns; column++) builder.Append(PlayerChar(cells[column][row])).Append(" | ");
             builder.AppendLine(sep);
         }
+        builder.Append("| ");
+        for (int column = 0; column < dimensions.Columns; column++)
+        {
+            builder.Append(column + 1).Append(" | ");
+        }
+        builder.AppendLine(sep);
         return builder.ToString();
     }