Explanations of test management on the IDE projects

We have explained how to install, fix a bug and contribute with a PR on https://www.github.com/eclipse-ide.

I am not sure that launching the tests (in Eclipse or with maven), is always easy or well explained. Tests already exist but should be highlighted in order to contribute to.

For this issue, I suggest to check on the main IDE projects how it is done and how it could be documented globally.