WWW at start of doc should match

A simple case: WWW

A longer version: WWWW shouldn't match the short one

This shouldn't match: aWWW nor this: WWWa.

This should: (WWW) as should this  *WWW*.

Multiword abbreviations like "Markdown Deep" should also work.



*[WWW]: World Wide Web
*[WWWW]: World Wide Web of Wonder :)
*[Markdown Deep]: Markdown made Better!