Update deploy-nodejs-with-docker tutorial

[matteocontrini]

As dicussed in #932, here's the updated tutorial.

A couple of things to decide on:

• Whether the tutorial date should be change to today, or if there's an "updated at" field that could be used to signal that the tutorial is up-to-date.
• Whether the automated builds section should be removed or updated, since that Docker Hub feature is no longer free and requires a paid subscription.

I have read and understood the Contributor's Certificate of Origin available at the end of
https://raw.githubusercontent.com/hetzneronline/community-content/master/tutorial-template.md
and I hereby certify that I meet the contribution criteria described in it.
Signed-off-by: Matteo Contrini matteo@contrini.it

[svenja11]

Thank you for taking the time to update your tutorial @matteocontrini!

• We don't have an "updated" field, so we usually just update the "date" field.
• Thank you for pointing that out. I removed the "automated builds" section but I did add a link to docker.docs » Set up Automated Builds. This should be enough.

I also added a small Node.js example so that anyone can follow the tutorial, even if they don't have a Node.js application ready yet.

[matteocontrini]

Thanks. I think you also need to:

• Remove or adapt this sentence referring to automated builds in the conclusions:

Setting up automated builds is useful and a first step into the Continuous Integration and Delivery world (CI/CD).

• Remove the images folder, which contains Docker Hub screenshots.