Issue #3438047: help hook

Closes #3438047

entity_embed_placeholder.module

 <?php
+use \Drupal\Core\Routing\RouteMatchInterface;
+
+/**
+ * Implements hook_help() for the Entity Embed Placeholder.
+ */
+function entity_embed_placeholder_help($route_name, RouteMatchInterface $route_match) {
+  // This is an empty implementation of hook_help().
+  $output = '';
+  $output .= '<p>' . t('This is Entity Embed Placeholder module') . '</p>';
+  return $output;
+}
 
 /**
  * @file