Give reader-friendly names to the `Step 1..n` parts

[eeue56]

E.g on here -> https://raorao.gitbooks.io/elmbridge-curriculum/content/The%20Elm%20Architecture.html

It's easier to understand what the "step" is if it has an English name, rather than a number

[raorao]

+1000. Current system is mostly the result of inertia / matching railsbridge syntax, but I think numbered subheadings would be an improvement.

tagging as an enhancement.