DOC-2502: Update code example for running tinymce in shadow dom. (#3429)

Author: kemister85

modules/ROOT/pages/shadow-dom.adoc

@@ -31,11 +31,12 @@ For example:
     // Do not use ‘selector’.
     target: node,
     plugins: [
-        "advlist autolink lists link image charmap print preview anchor",
-        "searchreplace visualblocks code fullscreen",
-        "insertdatetime media table help"
-    ].join(' '),
-    toolbar: "insertfile undo redo | styleselect | bold italic | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | link image"
+        "advlist", "anchor", "autolink", "charmap", "code", "fullscreen",
+        "help", "image", "insertdatetime", "link", "lists", "media",
+        "preview", "searchreplace", "table", "visualblocks",
+    ],
+    toolbar: "undo redo | styles | bold italic underline strikethrough | alignleft aligncenter alignright alignjustify | bullist numlist outdent indent | link image",
+
   });
 </script>
 ----