docs(orgchart): Add css workaround for missing connection lines in exported PDF

Author: pepinho24

controls/orgchart/appearance-and-styling/connecting-lines.md

@@ -84,3 +84,50 @@ If you want to add arrows to the ends of the connecting lines you can add the fo
 
 Such implementation is not supported in IE6 and IE7 browsers because they do not implement the **":after"** css selector.
 ![radorgchart-connecting-lines](images/radorgchart-connecting-lines.png)
+
+## Modify connection lines in exported PDF file
+
+The **RadClientExportManager** can be used to easily export the **RadOrgChart** to a PDF file as demonstrated in the [OrgChart - Export to PDF](https://demos.telerik.com/aspnet-ajax/client-export-manager/applicationscenarios/export-radorgchart/defaultcs.aspx?product=orgchart) online demo. 
+
+Due to a technical limitaion, the ClientExportManager cannot export the *:before* and *:after* pseudo elements that are actually the connecting lines of the RadOrgChart with Lightweight RenderMode. 
+
+Nevertheless, this issue is workarounded as of R2 2020, and for previous versions, the following CSS style can be used:
+
+````CSS
+.RadOrgChart .kendo-pdf-hide-pseudo-elements:after,
+.RadOrgChart .kendo-pdf-hide-pseudo-elements:before {
+  display: none !important; }
+
+.k-pdf-export .rocNode:before {
+  display: normal;
+  height: 0.3px;
+  max-width: 100%;
+  background: black; }
+
+.k-pdf-export .rocGroup:before,
+.k-pdf-export .rocGroup:after,
+.k-pdf-export .rocNode:after,
+.k-pdf-export .rocItem:after {
+  display: normal;
+  max-height: 100%;
+  width: 0.3px;
+  background: black; }
+
+.k-pdf-export .RadOrgChart.rocHorizontal .rocNode:before,
+.k-pdf-export.RadOrgChart.rocHorizontal .rocNode:before {
+  width: 0.3px; }
+
+.k-pdf-export.RadOrgChart.rocHorizontal .rocGroup:before,
+.k-pdf-export.RadOrgChart.rocHorizontal .rocGroup:after,
+.k-pdf-export.RadOrgChart.rocHorizontal .rocNode:after,
+.k-pdf-export.RadOrgChart.rocHorizontal .rocItem:after,
+.k-pdf-export .RadOrgChart.rocHorizontal .rocGroup:before,
+.k-pdf-export .RadOrgChart.rocHorizontal .rocGroup:after,
+.k-pdf-export .RadOrgChart.rocHorizontal .rocNode:after,
+.k-pdf-export .RadOrgChart.rocHorizontal .rocItem:after {
+  display: normal;
+  border-top: 0.3px solid black !important;
+  max-width: 100%;
+  height: 0.3px; }
+````
+