Resolve #3343657 "Hook help"

Closes #3343657

simplei.module

@@ -7,6 +7,21 @@
 
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Site\Settings;
+use Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Implements hook help.
+ */
+function simplei_help($route_name, RouteMatchInterface $route_match) {
+  switch ($route_name) {
+    case 'help.page.simplei':
+      $path = __DIR__ . '/README.txt';
+
+      if (file_exists($path)) {
+        return '<pre>' . file_get_contents($path) . '</pre>';
+      }
+  }
+}
 
 /**
  * Implements hook_page_attachments().
@@ -31,7 +46,7 @@ function simplei_page_attachments(array &$attachments) {
         $css = $anon;
       }
       elseif (is_bool($anon)) {
-        $css = "body:after { 
+        $css = "body:after {
           content: \"[$environment]\";
           position: fixed;
           top: 0;