[web] Added video tutorial by Dominik and Christian.

Many thanks to @dominik-kern and @cbsilver!

Preview link: https://ogs.ogs.xyz/-/ogs/-/jobs/29879/artifacts/web/public/docs/tools/getting-started/video-tutorial.html (supplemental links do not work here but will work on the website)

Youtube link: https://www.youtube.com/watch?v=BULunRJQRJ0&list=PLU_clTnZqNAeOXENl79kQwn0pgHGittX1

1. Feature description was added to the changelog