diff --git a/core/lib/Drupal/Core/Menu/ContextualLinkInterface.php b/core/lib/Drupal/Core/Menu/ContextualLinkInterface.php
index 04c2f7d..3560d9b 100644
--- a/core/lib/Drupal/Core/Menu/ContextualLinkInterface.php
+++ b/core/lib/Drupal/Core/Menu/ContextualLinkInterface.php
@@ -9,6 +9,14 @@
 
 /**
  * Defines a contextual link plugin.
+ *
+ * Contextual links by default are in the modulename.links.contextual.yml
+ * file. These YAML files contain a list of  contextual link plugin, keyed by the
+ * plugin id. Each definition must define a route_name and a group
+ * and might define title, options, and weight. See the getter methods on this
+ * interface for an explanation of each.
+ *
+ * @ingroup menu
  */
 interface ContextualLinkInterface {