I don’t see clear instructions about how to clone the repository at the first commit and groll it forward. Is the repository meant to be used at all? Or is it just there as a reference, so that at any point someone following the tutorial can compare their code with the corresponding commit to see if they followed the instructions correctly? (This could be clarified in the tutorial.)
Either way it would be useful to have tags on each commit, like 1.x-step2 etc. Then someone can git clone -b 1.x-step1, or easily pull up the repo at step 3 in the GitHub UI.
The readme at head could definitely be made clear. Something to the effect of “this is what you should have if you followed [url] all the way through.”
You could update the readme similarly at each step, that might make it slightly less confusing for someone jumping around via the github UI.