Try to explain better where and why Eliot is useful - fixes 137

Fixes #137.
:question: Syntax highlighting makes this look better in my opinion

![screenshot 2014-12-10 10 06 09](https://cloud.githubusercontent.com/assets/797801/5374107/64105fe4-8054-11e4-9af3-048541bba4ad.png)

vs

![screenshot 2014-12-10 10 06 49](https://cloud.githubusercontent.com/assets/797801/5374111/6a3743d8-8054-11e4-8ba8-3d84b9598fd9.png)