More documentation on building, running, and debugging

[NimaiMalle]

The Start Contribution section describes how to initialize and build the project, and how to run the tests, but not how to run the built jscpd cli.

Please add instructions on how to run the built command line tool, specifically how to launch and debug the tool.

I have been trying to create a working Visual Studio Code debug launch configuration, but have been running into all sorts of issues about module resolution, etc.

Thank you!