Requirements in notes

[annevk]

Notes should only be used to explain things already required elsewhere. They cannot themselves contain requirements.

Examples of bad notes:

Note: When a document is closed, the user agent MUST implicitly call unlock() so that the [system key press handler=] (if any) is unregistered.

Note: When implementing this API, user agents should take care not to change the order in which keyboard events are dispatched to the page. Keys that are included in the set of reserved key codes must be dispatched in the same relative order that they would have been sent had they not been included in the set.