documentation changes: 1) added an example of how to create an app-wide ...

Just some documentation changes:

1) Added an "App-wide views" section to the README file. This is basically a knock-off of the example given in the co-views README, and it's probably obvious to anyone familiar with generators or Koa. But it took me a little bit to figure out the slight difference, so it may be worth adding to spare others in the future.

2) Fixed a type in the underscore example

Cheers,
--Rick