Add documentation for `Suppressor`s

[BraisGabin]

The Suppressors is a new concpet introduced in detekt 1.19.0 to give more flexibilty to ignore some issues. But it is not documented yet. So we should add a new documentation to it.

The problem here is: should it be automated? So any new Suppressor automatically adds it's documentation? Or should iy be an static code?

[schalkms]

In my opinion, it could be a mixture of both.

1. Use a separate entry on detekt's home page.
2. Document the code inline. This way, one can look into the code and grasp more details if necessary.