Document integrated Import flow

Dev Issue: https://issues.redhat.com/browse/ODC-5009

Marvel Design: https://marvelapp.com/prototype/5aha4ie/screen/79451023

The import from Git, Devfile and Dockerfile are now going to be integrated. 

Existing module only cover Git codebase flow

This might need us to create a new module using the new integrated flow and maybe we can cover import using Devfile, so that in the long run we can cover as many options as possible. Since Git is already covered, we can simply modify the starting steps of the existing git section