added videoio docs and tutorials

doc/tutorials/tutorials.markdown

@@ -71,6 +71,10 @@ As always, we would be happy to hear your comments and receive your contribution
 
     Run OpenCV and your vision apps on an iDevice
 
+-   @subpage tutorial_table_of_content_videoio
+
+    These tutorials show how to read and write videos using videio module.
+
 -   @subpage tutorial_table_of_content_viz
 
     These tutorials show how to use Viz module effectively.