[wwwdocs] Mention libstdc++-v3 <regex> in 4.9 changes.html

[Paolo Carlini]

Hi,

On 10/02/2013 12:19 PM, Gerald Pfeifer wrote:
> On Tue, 1 Oct 2013, Tim Shen wrote:
>> Hi, libstdc++-v3 <regex> is ready for releasing.
> Nice!
>
>> Is it Ok to apply? By the way, do we need a News entry for this
>> improvement?
> Yes, and yes. :-)
>
> Just one question "improved experimental support" sounds a bit
> weak.  I think I understand where it is coming from, but is there
> a way to market this a bit stronger?
Minimally, I would talk about "improved support": the evolution from 
-std=c++0x to -std=c++11 meant that we aren't in experimental mode anymore.

Paolo.