Whether to embed related resources in the response. It can be true when we want to embed all available resources, or a string like "givewp:statistics" when we wish to embed only a specific one. Available embeddable resources: givewp:statistics | givewp:donations | givewp:subscriptions. IMPORTANT: Use with caution when setting to true, as donations and subscriptions return 30 items by default, which can result in a large payload.