REST API: Content update should clear caches

[eteubert]

Content changes using the forms in the WordPress admin are trigger a cache purge:

\Podlove\Cache\TemplateCache::get_instance()->setup_purge();

However, when using the REST API, this does not happen yet. So changes made via the REST API are not immediately visible to visitors.

Instead, all modifying operations (create, update, delete) affecting public data should call the cache purge above.

(Alternatively, add an API endpoint to clear the caches. But I don't think that this is a responsibility for the API user. It should happen automatically.)

via podlove/documentation#42