I looked at similar questions on StackExchange and on these forums, but the selected answers didn't work for me. That is why I'm asking this question.

I have been following this tutorial to create my own custom Dupral 8 module. From what I can tell, I have the right file stucture and correct content in my files, but I get a page not found error. I have tried using leading slahes on the _controller in the photoshelter.routing.yml file and in the namespace declarations in the PhotoController.php file, but that hasn't changed anything. I have run out of ideas to try. Does anyone have any trouble shooting suggestions of spot errors in these files?

PhotoController.php

namespace Drupal\photoshelter\Controller;
use Drupal\Core\Controller\ControllerBase;

class PhotoController extends ControllerBase {
  public function content() {
    return array(
      '#type' => 'markup',
      '#markup' => $this->t('Hello, World!'),
    );
  }
}

photoshelter.info.yml

name: PhotoShelter API
description: Integrate the PhotoShelter API with your Drupal site.
package: Custom
type: module
core: 8.x
configure: photoshelter.settings
php: 5.6

photoshelter.routing.yml

photoshelter.content:
  path: '/photoshelter'
  defaults:
    _controller: '\Drupal\photoshelter\Controller\PhotoController::content'
    _title: 'PhotoShelter API'
  requirements:
    _permission: 'access content'

File Structure

photoshelter
  -src
    -Controller
      PhotoController.php
  info/routing.yml files