Fix various code examples in documentation

doc/classes/Array.xml

@@ -21,11 +21,11 @@
 		var array = new Godot.Collections.Array{"First", 2, 3, "Last"};
 		GD.Print(array[0]); // Prints "First"
 		GD.Print(array[2]); // Prints 3
-		GD.Print(array[array.Count - 1]); // Prints "Last"
+		GD.Print(array[^1]); // Prints "Last"
 
-		array[2] = "Second";
+		array[1] = "Second";
 		GD.Print(array[1]); // Prints "Second"
-		GD.Print(array[array.Count - 3]); // Prints "Second"
+		GD.Print(array[^3]); // Prints "Second"
 		[/csharp]
 		[/codeblocks]
 		[b]Note:[/b] Arrays are always passed by [b]reference[/b]. To get a copy of an array that can be modified independently of the original array, use [method duplicate].

doc/classes/DTLSServer.xml

@@ -28,7 +28,7 @@
 		        if dtls_peer.get_status() != PacketPeerDTLS.STATUS_HANDSHAKING:
 		            continue # It is normal that 50% of the connections fails due to cookie exchange.
 		        print("Peer connected!")
-		        peers.append(dtls_peer)
+		        peers.append(TlsOptions.server(dtls_peer))
 
 		    for p in peers:
 		        p.poll() # Must poll to update the state.
@@ -57,7 +57,7 @@
 
 		    public override void _Process(double delta)
 		    {
-		        while (Server.IsConnectionAvailable())
+		        while (_server.IsConnectionAvailable())
 		        {
 		            PacketPeerUdp peer = _server.TakeConnection();
 		            PacketPeerDtls dtlsPeer = _dtls.TakeConnection(peer);
@@ -66,7 +66,7 @@
 		                continue; // It is normal that 50% of the connections fails due to cookie exchange.
 		            }
 		            GD.Print("Peer connected!");
-		            _peers.Add(dtlsPeer);
+		            _peers.Add(TlsOptions.Server(dtlsPeer));
 		        }
 
 		        foreach (var p in _peers)

doc/classes/Window.xml

@@ -638,13 +638,13 @@
 			[/gdscript]
 			[csharp]
 			// Set region, using Path2D node.
-			GetNode<Window>("Window").MousePassthrough = GetNode<Path2D>("Path2D").Curve.GetBakedPoints();
+			GetNode<Window>("Window").MousePassthroughPolygon = GetNode<Path2D>("Path2D").Curve.GetBakedPoints();
 
 			// Set region, using Polygon2D node.
-			GetNode<Window>("Window").MousePassthrough = GetNode<Polygon2D>("Polygon2D").Polygon;
+			GetNode<Window>("Window").MousePassthroughPolygon = GetNode<Polygon2D>("Polygon2D").Polygon;
 
 			// Reset region to default.
-			GetNode<Window>("Window").MousePassthrough = new Vector2[] {};
+			GetNode<Window>("Window").MousePassthroughPolygon = new Vector2[] {};
 			[/csharp]
 			[/codeblocks]
 			[b]Note:[/b] This property is ignored if [member mouse_passthrough] is set to [code]true[/code].