Dockers documentation is actually pretty good, I’d recommend taking a look at it because it’s written really well and can be used as a decent primer on learning to read documentation.
I would recommend learning docker / containerization. For your use case you likely won’t see a big benefit HOWEVER it is a good technology to know.
As far as the “why” you’d use it there are too many to list but for your use case the why I’d argue is “just so you know how to do it” and you’ll come up with your own why along the way.
Simplest why beyond “it’s a good technology to know” is that updating an app is as simple as pulling a new container and relaunching it.