added introduction to cvat and datumaro doc (#5236)

site/content/en/docs/getting_started/product_tour/cvat-intro.md

 ---
-title: 'Cvat intro'
-linkTitle: 'Cvat intro'
+title: 'CVAT intro'
+linkTitle: 'CVAT intro'
 weight: 1
 ---
 

site/content/en/docs/getting_started/product_tour/introduction-to-cvat-and-datumaro.md

+---
+title: 'Introduction to CVAT and Datumaro'
+linkTitle: 'Introduction to CVAT and Datumaro'
+weight: 2
+---
+
+We are excited to introduce the first video in our course series designed to help you
+annotate data faster and better using CVAT.
+In this introductory 4 minute video, we walk through:
+1. what problems CVAT and Datumaro solve,
+1. how they can speed up your model training process, and
+1. some resources you can use to learn more about how to use them.
+
+<iframe width="560" height="315" src="https://www.youtube.com/embed/GgKIEFhd1CY" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>