Clarify "Simple Routes" introductory sentence

(Ember newb here). As far as I can tell, the sentence was meant to convey that each route has a controller and template with the same name as the route.
Merge pull request #451 from cliftonaddepar/patch-1

Clarify "Simple Routes" introductory sentence
link to s3 builds on models index page
Merge pull request #453 from fivetanley/reference-s3-builds

link to s3 builds on models index page