Add Aragon One's recommended development flow

[sohkai]

It'd help new developers getting started to have a recommended workflow for their own apps.

At Aragon One, we typically develop apps following this flow:

1. Define requirements for the app:
   • Contract: storage, getters, and events
   • Frontend: mock ups
2. Build contract
3. Build frontend
   1. Build self-contained UI components
   2. Unify components into an implementation of the design that uses mock data (usually just a JSON file)
   3. Connect UI to real chain data
   4. Allowing users to "write" data by creating transactions