update c# class examples

tutorials/networking/http_client_class.rst

@@ -124,7 +124,9 @@ It will connect and fetch a website.
 
  .. code-tab:: csharp
 
-    class HTTPTest : SceneTree
+    using Godot;
+
+    public partial class HTTPTest : SceneTree
     {
         // HTTPClient demo.
         // This simple class can make HTTP requests; it will not block, but it needs to be polled.

tutorials/networking/http_request_class.rst

@@ -48,7 +48,9 @@ Below is all the code we need to make it work. The URL points to an online API m
 
     .. code-tab:: csharp
 
-        class HTTPRequestDemo : CanvasLayer
+        using Godot;
+        
+        public partial class HTTPRequestDemo : CanvasLayer
         {
             public override void _Ready()
             {