Improve JSDocs

[jabrena]

Idea:
https://shaka-player-demo.appspot.com/docs/tutorial-live.html
https://github.com/google/shaka-player/blob/master/jsdoc.conf.json
https://github.com/google/shaka-player/tree/master/tutorials
https://github.com/google/shaka-player/blob/master/build/docs.sh