Update contributing guide with new video links (#40426)

* Update contributing guide with new links

* Update CONTRIBUTING.md

Author: logankilpatrick

CONTRIBUTING.md

@@ -6,7 +6,7 @@ If you are already familiar with Julia itself, this blog post by Katharine Hyatt
 
 ## Learning Julia
 
-[The learning page](https://julialang.org/learning) has a great list of resources for new and experienced users alike. [This tutorial video](https://www.youtube.com/watch?v=vWkgEddb4-A) is one recommended starting point, as is the "[Invitation to Julia](https://www.youtube.com/watch?v=gQ1y5NUD_RI)" workshop video from JuliaCon 2015  ([slide materials here](https://github.com/dpsanders/invitation_to_julia)). The [Julia documentation](https://docs.julialang.org) covers the language and core library features, and is searchable.
+[The learning page](https://julialang.org/learning) has a great list of resources for new and experienced users alike.
 
 ## Before filing an issue