hook_entity_reference_selection_alter() is undocumented

Problem/Motivation

SelectionPluginManager does:

    $this->alterInfo('entity_reference_selection');

But I can't find hook_entity_reference_selection_alter documented in any api.php file.

Steps to reproduce

Proposed resolution

Write the documentation. This should go in core/lib/Drupal/Core/Entity/entity.api.php.

Use another alter hook for a plugin type as a template, e.g. hook_views_plugins_access_alter

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet