Add video link to Containers Plumbing talk

[gbraad]

The file content/posts/2023-03-22-containers-plumbing.md contains a link to a video, but this is not very clear. It would be better to add a static image with a clear 'play' button to indicate this is a video. This can be followed by the link to the slides. This puts more emphasize on the content in a visual way.

Also, I in the post is not clear. This needs to be substituted with a LinkedIn or GitHub profile of the author (Christophe).