tutorial-06: reorganize tutorial with steps

[lnielsen]

The README doesn't follow the same structure as the previous tutorials. I would expect a couple of steps with a bit of text and images. I think most of it can just be taken from the presentation.

• Step 1: Inspect project structure
• Step 2: Initialize the git repository
• Step 3: Build the documentation
• Step 4: Running tests
• Step 5: End-to-end testing
• Step 6: Fix the failing test
• Step 7: Installing a new Python dependency

[kpsherva]

done