Create Documentation

[echo66]

• [ ] How to use the annotator interface.
• [ ] Design decisions related to data-server.js.
• [ ] Design decisions related to annotations-track-ctr.js and annotations-board-ctr.js.
• [ ] Open issues in the implementation.
• [ ] Events for custom wavesurfer.js implementation.
• [ ] Events for data-server.js.
• [ ] Events for annotations-track-ctr.js.