Editorial: String.prototype.normalize references the Unicode Standard instead of Annex 15

[dewren99]

Changed the reference String.prototype.normalize is using as per #912

Please let me know if any further changes are needed, thanks!

[mathiasbynens]

Since #620 the ECMAScript spec refers to the latest available Unicode version rather than any particular version. We could accomplish this here by changing the link to https://www.unicode.org/versions/latest/ch03.pdf and updating the text accordingly.

[dewren99]

Updated the link and the text to refer to the latest Unicode Standard. I wasn't sure what would be the best text to represent the changes, let me know if you would prefer to use another specific text to display.

[dewren99]

@mathiasbynens Also would it be better to not mention the section number 3.11? I'm not sure if the section numbering would kept the same in future versions.

[michaelficarra]

@dewren99 We discussed this in the editor call today. Let's drop the section number and only refer to the section by its name.

[dewren99]

@michaelficarra Should I be keeping this branch up to date with the main until it's merged? I'm not sure what the preferred method is for this repo

[ljharb]

@dewren99 if there's no conflicts, you shouldn't need to, as I'll rebase it before it lands as a matter of course. Feel free to rebase it yourself as you like, though.