Add DocConfirmed extension method to Resource.cs

Added a new DocConfirmed extension method to the Extensions class in Resource.cs. This method enables retrieval of the "DocConfirmed" localized string via IStringLocalizer, similar to the existing DocSigned method.

EnvelopeGenerator.Application/Resources/Resource.cs

@@ -204,6 +204,13 @@ public static class Extensions
     /// <returns></returns>
     public static string DocSigned(this IStringLocalizer localizer) => localizer[nameof(DocSigned)].Value;
 
+    /// <summary>
+    /// 
+    /// </summary>
+    /// <param name="localizer"></param>
+    /// <returns></returns>
+    public static string DocConfirmed(this IStringLocalizer localizer) => localizer[nameof(DocConfirmed)].Value;
+
     /// <summary>
     /// 
     /// </summary>