README doesn't specify suggested mirrors for Make, Maven, and JDK

[zachfejes]

Hey folks, just trying to get an image of the yamcs quickstart up and running - and I'm running into some trouble - it may be useful to include the specifics/links to the version of Make, Maven, and JDK that you recommend using.

[fqqb]

Hi, I thinks it's already there: JDK11 and Maven 3.1:
https://github.com/yamcs/quickstart/blob/master/README.md

These are minimum versions, anything later should do as well. If you have specific errors, I can have a look.

I think I'll add mvnw wrapper scripts to the repository, to make the use of Maven a little easier (mvnw is a shell script that will automatically download an appropriate version of Maven).

I think you are looking at the README inside the docker directory, this directory is optional.