feat(doc): remove old video tutorial link

Author: manushak

README.md

@@ -64,12 +64,6 @@ if-run -h
 
 Please read our documentation at [if.greensoftware.foundation](https://if.greensoftware.foundation/)
 
-## Video walk-through
-
-Watch this video to learn how to create and run a `manifest`.
-
-[![Watch the walk-through video](https://i3.ytimg.com/vi/R-6eDM8AsvY/maxresdefault.jpg)](https://youtu.be/GW37Qd4AQbU)
-
 ## Join our mailing list
 
 We have a public mailing list at [if-community@greensoftware.foundation](https://groups.google.com/u/1/a/greensoftware.foundation/g/if-community). We send out weekly updates that explain what we've shipped, what we're working on and how you can get involved each week!