Documentation and comments: Add links to Web Audio API

[uklotzde]

Add links to https://webaudio.github.io/web-audio-api were applicable. The information in the spec should not be duplicated apart from a short summary in doc comments. Only deviations from the spec should be noted in detail.

This applies to both public doc comments and internal code comments.

Adding a short advice for developers should suffice for closing this issue.

[uklotzde]

Example why this would be helpful: https://github.com/orottier/web-audio-api-rs/pull/293#issuecomment-1596573632