I also read that article before, it was very useful, I also found a similar one, if it helps: Getting started with the new CodeMirror 6 | DataCamp Engineering
But IMHO, the best way to learn would be to experiment around with the examples on a local repo, to look at this form for help and to look at the references docs. To get started the articles send by you, and the one above really helps.
The examples I found to be initial for me to start(I would recommend to reading all the examples to your requirement, but I found these to be essential):
- CodeMirror System Guide - A overview, and general guide to using CM, there is a lot of content, but it really helps in understanding how things may work
- CodeMirror Configuration Example - My main takeaway, which took me way longer then it should have been was the fact extensions are imported here, every example doesn’t state this, and it was very confusing to get started
For me the biggest reason for being able to move forward was getting these examples to run on a local repo, and experimenting with it, it really helps.