Use full user path instead of ~

[mauricio-tki]

Step 1a-1d refer to the directory containing code as /Users/bertozzivill/repos/map-itn-cube/stock_and_flow, while this one uses ~. The consistency makes it easier to run the model in docker.

If you prefer, I could instead change step 1a-1d to use ~/repos/...

This is just an intermediate step, at a later stage I'd like to add the option to pass in paths to step 1 and 2 (similar to step 3+).

[bertozzivill]

Sounds good to me, thanks.