Dead link in README

[john-aws]

The README contains a link to https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Parser_API, which is dead.

I could not immediately locate an existing Mozilla page that mirrored the contents of the original page (viewable via Wayback Machine here), otherwise I would have submitted a PR.

[RReverser]

Oh, huh. I guess the closest version is here, but also marked for deletion. Maybe we should just like to Wayback Machine version, since it's just a historical link anyway.