Add synchronous version of CreateArticleAsync with XML documentation

src/Leanetec.EConnect.Client/Articles/PostExtensions.cs

@@ -19,4 +19,15 @@ public static class PostExtensions
     {
         ApiVersion = apiVersion
     });
+
+    /// <summary>
+    /// Sends a request to create a new <see cref="Article"/> using MediatR.
+    /// </summary>
+    /// <param name="mediator">The <see cref="IMediator"/> instance used to send the request.</param>
+    /// <param name="article">The <see cref="Article"/> entity to be created.</param>
+    /// <param name="apiVersion">Optional API version to include in the request.</param>
+    public static void CreateArticle(this IMediator mediator, Article article, int? apiVersion = null) => mediator.Send(new PostRequest(article)
+    {
+        ApiVersion = apiVersion
+    }).GetAwaiter().GetResult();
 }