fix new event documentation

[sualko]

No description provided.

[nickvergessen]

Looks good in general, apart from the setObject change

[sualko]

This pr just reflects the code documentation: https://github.com/nextcloud/server/blob/f91a85c32eb4a4c3cef20e0daab4069437df5d07/lib/public/Activity/IManager.php#L38-L51

        /**
	 * Generates a new IEvent object
	 *
	 * Make sure to call at least the following methods before sending it to the
	 * app with via the publish() method:
	 *  - setApp()
	 *  - setType()
	 *  - setAffectedUser()
	 *  - setSubject()
	 *
	 * @return IEvent
	 * @since 8.2.0
	 */
	public function generateEvent(): IEvent;

So if setObject should be mandatory, at lest the code should be updated as well. Btw I have no clue what the difference is between all those functions. I can only make an reasonable assumption based on other apps, but I'm not sure what is best practice and how should it be used. Therefore some documentation from someone with more knowledge would be helpful.

[nickvergessen]

Ah oh... hmm then let me fix server and you move setObject() back here

[sualko]

you move setObject() back here

No problem. Done.