http://guides.rubyonrails.org/routing.html#crud-verbs-and-actions
creates seven different routes in your application, all mapping to the Photos controller:
| HTTP Verb | Path | Controller#Action | Used for |
|---|---|---|---|
| GET | /photos | photos#index | display a list of all photos |
| GET | /photos/new | photos#new | return an HTML form for creating a new photo |
| POST | /photos | photos#create | create a new photo |
| GET | /photos/:id | photos#show | display a specific photo |
| GET | /photos/:id/edit | photos#edit | return an HTML form for editing a photo |
| PATCH/PUT | /photos/:id | photos#update | update a specific photo |
| DELETE | /photos/:id | photos#destroy | delete a specific photo |