Issue #2862751 by Jo Fitzgerald, phenaproxima: Add documentation to...

Issue #2862751 by Jo Fitzgerald, phenaproxima: Add documentation to PerComponentEntityDisplay destination plugin

core/modules/migrate/src/Plugin/migrate/destination/PerComponentEntityDisplay.php

@@ -5,6 +5,45 @@
 /**
  * This class imports one component of an entity display.
  *
+ * Destination properties expected in the imported row:
+ * - entity_type: The entity type ID.
+ * - bundle: The entity bundle.
+ * - view_mode: The machine name of the view mode.
+ * - field_name: The machine name of the field to be imported into the display.
+ * - options: (optional) An array of options for displaying the field in this
+ *   view mode.
+ *
+ * Examples:
+ *
+ * @code
+ * source:
+ *   constants:
+ *     entity_type: user
+ *     bundle: user
+ *     view_mode: default
+ *     field_name: user_picture
+ *     type: image
+ *     options:
+ *       label: hidden
+ *       settings:
+ *         image_style: ''
+ *         image_link: content
+ * process:
+ *   entity_type: 'constants/entity_type'
+ *   bundle: 'constants/bundle'
+ *   view_mode: 'constants/view_mode'
+ *   field_name: 'constants/field_name'
+ *   type: 'constants/type'
+ *   options: 'constants/options'
+ *   'options/type': '@type'
+ * destination:
+ *   plugin: component_entity_display
+ * @endcode
+ *
+ * This will add the "user_picture" image field to the "default" view mode of
+ * the "user" bundle of the "user" entity type with options as defined by the
+ * "options" constant, for example the label will be hidden.
+ *
  * @MigrateDestination(
  *   id = "component_entity_display"
  * )