Did you create these?

I think they are just trying to promote the two links near the end of the article.

Does this mean your entire desktop environment is a Docker container? Or are you using the docker container to setup on the host?

No, not on the host. The containers run on the host and provide the environment. They are isolated from the host.

Is all the content on that website representative of what is in the book when you buy it?

Not a dumb question at all. Hotswappable switches are becoming more common but many keyboard enthusiasts still are iffy about them. Hotswappable switches tend to have a bit more wobble that their soddered counterparts, but in my opinion the benefit of being able to change out the switches outweighs the wobble.

Those who are confident in their switch choice will prefer less wobble, and probably have multiple keyboards anyway with different switches.