word-count.js documentation

[jipmoors]

Added documentation to the word-count.js file.
Especially interesting are the obscure characters and character-ranges used in the regular expressions.

This patch was a joined effort of myself and ​andizer.

No functionality has been altered.

[jipmoors]

word-count.js documented

[obenland]

IANDE (I Am No Documentation Expert), but I think all comments should be preceded by a blank line, at least that's what ​wpcs keeps telling me.

[adamsilverstein]

Great work here @jipmoors thanks for taking this on - the lack of documentation in these older JS files is sorely in need of addressing. I agree the extra space before comment lines would be helpful and inline with standards.

[jipmoors]

Added newlines before comments and converted multiple lines to multi-line comment block.

[jipmoors]

While going over the file to apply the new lines above comments I noticed some minor improvements.

It felt a bit strange to put new lines in the comments on the list of regular expressions being defined, I guess the consistency break between items in the list bugged me a bit.

I guess the clarity of where the comment belongs to wins in regard to consistency, I was reluctant to add comments above every entry to balance it out the other way around.

Please give props to andizer as well (as mentioned before).
Noting here explicitly because he was forgotten in 37717.

[wonderboymusic]

In 38358:

Editor: improve word-count.js documentation.

Props jipmoors, andizer.
Fixes #37718.

[SergeyBiryukov]

In 39739:

Docs: Use 3-digit, x.x.x style semantic versioning for @since entries in wp-admin/js/word-count.js.

See #37718.

[adamsilverstein]

Thanks @SergeyBiryukov!