Add a section about MySQL to Supporting Systems

I am trying to run the sirmordred tests. First I needed to get an ElasticSearch instance up locally. Now it looks like I need a MySQL DB as well. There is no mention of MySQL under the Supporting Systems section of the tutorial. Should that be added? If so, any suggestions on how to (quickly) do so, maybe via docker? Do the maintainers of the project have any shortcuts for this?

Related question around the Supporting Systems section of the tutorial: the table of contents has several related bits that are scattered around the document. I wonder if it makes sense to combine certain sections together (and maybe split them up under related sub-sections)? For example, there is a section around installing ElasticSearch, another section around installing Kibana, and a final (and, arguably, most useful / best for newcomers) section around installing both using Docker. In my opinion, we should direct newcomers to installing the docker ES+Kibana container first, as it is (to me) the most convenient of the three options. Perhaps we can combine the current ES, Kibana and ES+Kibana documentation into one section and re-order to put docker installation instructions at the top?

Let me know what the team thinks. I am happy to put together a PR for this if I can get direction from the team.

Cheers,
Fil