Add information how to use a debugger with the cms

[david-venhoff]

Motivation

Using a debugger with the cms is not trivial, since our project structure does not match the default django project structure (Running python integreat_cms/integreat-cms-cli runserver fails)

Proposed Solution

Add documentation how to properly configure a debugger for the cms using various editors.

Alternatives

Don't and let people figure it out by themselves or use print-debugging

User Story

As a developer I want to use a debugger with the cms

Additional Context

Launch config for vscode: https://chat.tuerantuer.org/digitalfabrik/pl/4s6rsr9hobd7jfbyja1x45bdsy