[css-text-3] References to UAX* link to very old versions

[frivoal]

[UAX11] is http://www.unicode.org/unicode/reports/tr11/tr11-8.html from 2001-03-23.
The latest version is http://www.unicode.org/reports/tr11/tr11-31.html from 2016-05-18.

[UAX14] is http://www.unicode.org/unicode/reports/tr14/tr14-17.html from 2005-08-29.
The latest version is http://www.unicode.org/reports/tr14/tr14-37.html from 2016-06-01.

[UAX24] http://www.unicode.org/unicode/reports/tr24/tr24-7.html from 2005-03-28.
The latest version is http://www.unicode.org/reports/tr24/tr24-26.html from 2016-05-18.

[UAX29] is http://www.unicode.org/unicode/reports/tr29/tr29-9.html from 2005-03-25.
The latest version is http://www.unicode.org/reports/tr29/tr29-29.html from 2016-06-20.

I believe this is not intentional, but rather an artifact of the tools and databases (CC: @tabatkins @plinss) that we use to do the auto-linking, but it seems that a being out of date by a decade+ should make us react somehow.

[frivoal]

Duplicated by #1169. Since the discussion made progress there, closing this one.