Jumpstart `eoc-dev`

[Mega-JC]

We need to set up this repository according to Weekly Challenges 2.0: Era of Challenges.

The main branch can contain a template repository structure from which other c<xxx>_challenge_name/template branches can be created.

A README.md can contain the recurring steps required to download and work on a specific challenge. As such, it will be slightly different for every challenge.

• Add generic README.md on the main branch
• Add generic repository structure