Remove Docker Desktop from Readme

Docker Desktop is not needed for Windows users and should be removed from Readme. Instead of having to use Docker Desktop, since we are already on WSL and Debian, we can just install Docker in Debian (comes with Docker Engine and Docker Compose). No need for extra useless apps on the Windows side. :)

My suggestion: replace this text:

Windows and macOS users use Docker Desktop which already ships Docker Compose v2.

With this:

• Windows users must first install Debian on WSL and can then install Docker directly in Debian.

• macOS users use Docker Desktop which already ships Docker Compose v2.

(For macOS, I don't know if Docker Desktop is still necessary)