[Documentation]: Extend Test coverage documentation

[jonniebigodes]

Describe the problem

Reported in here.

The documentation needs a bit of a change to include some additional context on some of its features, potentially aimed at larger projects.

@yannbf can you let us know if this is accurate and potentially other additions you may find useful so that we can adjust accordingly?

Additional context

No response

[yannbf]

@jonniebigodes sorry for checking this just now, but in short, the coverage functionality uses nyc, and whatever nyc configuration people use, will be used in the project.

Users can just check the documentation of nyc for instance here and here.