replaced Revit 2020 SDK by Revit 2021 SDK

SDK/Samples/SampleCommandsSteelElements/CS/UpdateConnectionDetailedParameters.cs

@@ -8,7 +8,7 @@ using Autodesk.Revit.UI.Selection;
 using Autodesk.AdvanceSteel.CADAccess;
 using Autodesk.AdvanceSteel.Geometry;
 using Autodesk.AdvanceSteel.Modelling;
-using RvtDwgAddon;
+using Autodesk.SteelConnectionsDB;
 using Autodesk.Revit.DB;
 using Autodesk.Revit.DB.Structure;
 using Autodesk.Revit.UI;
@@ -25,6 +25,22 @@ namespace Revit.SDK.Samples.SampleCommandsSteelElements.UpdateConnectionDetailed
    [Autodesk.Revit.Attributes.Journaling(Autodesk.Revit.Attributes.JournalingMode.NoCommandData)]
    public class Command : IExternalCommand
    {
+      /// <summary>
+      /// Implement this method as an external command for Revit.
+      /// </summary>
+      /// <param name="commandData">An object that is passed to the external application 
+      /// which contains data related to the command, 
+      /// such as the application object and active view.</param>
+      /// <param name="message">A message that can be set by the external application 
+      /// which will be displayed if a failure or cancellation is returned by 
+      /// the external command.</param>
+      /// <param name="elements">A set of elements to which the external application 
+      /// can add elements that are to be highlighted in case of failure or cancellation.</param>
+      /// <returns>Return the status of the external command. 
+      /// A result of Succeeded means that the API external method functioned as expected. 
+      /// Cancelled can be used to signify that the user cancelled the external operation 
+      /// at some point. Failure should be returned if the application is unable to proceed with 
+      /// the operation.</returns>
       public virtual Result Execute(ExternalCommandData commandData, ref string message, ElementSet elements)
       {
          UIDocument activeDoc = commandData.Application.ActiveUIDocument;