Create `index.html`

[bartaelterman]

This is the main page for the visualization and should include:

• [x] sections for documentation
• [x] a map of Belgium displaying the blackout data
• [x] elements that allow the user to interact with the map (highlight different sections)

[bartaelterman]

@peterdesmet : code added to interact with the map: https://github.com/Datafable/rolling-blackout-belgium/commit/9140bb903545111a6185eb9108571278ae980e0b

Add your cartocss here.