Add some existing examples

dotnet/uniconta/CreateInvoiceReportPdf.cs

@@ -0,0 +1,29 @@
+public async Task CreateOfferReport(CrudAPI api, GiftProject giftProject)
+{
+    var order = ConvertProjectToOrder(giftProject);
+
+    var invoiceParams = new InvoiceParameters()
+    {
+        Date = DateTime.Now,
+        InvoiceNumber = order.Name,
+        order = order,
+        lines = order.OfferLines,
+        ReturnPDF = true,
+        SendByOutlook = false,
+        SendXML = false,
+        DocumentType = CompanyLayoutType.Offer,
+        ShowInvoice = false,
+        Simulate = false
+    };
+    var invoice = await invoiceParams.PostInvoice(new InvoiceAPI(api));
+    var data = invoice.pdf;
+
+    var fileName = "Offerte 123";
+    var attachment = new UserDocsClient()
+    {
+        _Data = data,
+        _Text = fileName,
+        _DocumentType = FileextensionsTypes.PDF
+    };
+    return attachment;
+}