Redesign "Lessons and Resources" page

[malenki]

There are at least three duplicates:

• Scott Murray's D3 Tutorials
• Interactive Data Visualization for the Web An expanded version of this tutorial can be found in his book
• D3 Mike Bostock (creator of D3) has collected a list of D3 tutorials many written by him. They include links to talks and video examples

[geobrando]

Duplicates are rendered because we're using multiple tags for each resource, as you can see here. Agree that this is slightly awkward and could be improved.

[rhewitt22]

@geobrando @malenki

My original intent in creating the page was that as the list grew each topic could have a dedicated page. This is preferable to a page that's 100 miles long and full of nothing but text.