docs/api: add info to 'trigger' method

[Kogoruhn]

Hi! No component in docs api contain a notice about trigger('event'), that without parameter { bubbles: true } events doesnt bubbling. Please, add this.

[gkatsev]

Are you talking about in this section? https://docs.videojs.com/module-events.html#trigger

If so, the docs for it is generated in the main repo (https://github.com/videojs/video.js/blob/master/src/js/utils/events.js#L388-L404), would you be able to make a PR? Thanks