diff --git a/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php b/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php
index afc6036..062453a 100644
--- a/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php
+++ b/core/modules/entity_reference/src/Annotation/EntityReferenceSelection.php
@@ -12,6 +12,12 @@
 /**
  * Defines a EntityReferenceSelection annotation object.
  *
+ * Plugin Namespace: Plugin\Action
+ * For a working example, see \Drupal\comment\Plugin\entity_reference\selection\CommentSelection
+ *
+ * @see \Drupal\entity_reference\Plugin\Type\SelectionPluginManager
+ * @see plugin_api
+ *
  * @Annotation
  */
 class EntityReferenceSelection extends Plugin {
diff --git a/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php b/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php
index aa44f1c..0bcc129 100644
--- a/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php
+++ b/core/modules/entity_reference/src/Plugin/Type/SelectionPluginManager.php
@@ -19,6 +19,9 @@
 
 /**
  * Plugin type manager for the Entity Reference Selection plugin.
+ *
+ * @see \Drupal\entity_reference\Annotation\EntityReferenceSelection
+ * @see plugin_api
  */
 class SelectionPluginManager extends DefaultPluginManager {