[wwwdocs] document new options in gcc-8/changes.html

[Martin Sebor]

On 04/04/2018 05:03 PM, Paolo Carlini wrote:
> Hi Martin
>
> On 05/04/2018 00:28, Martin Sebor wrote:
>> +      implementations do suppresses the warning.</li>
> suppress

I was about to fix this but re-reading the full sentence made
me realize it's correct as is:

   Note that due to GCC bug 82944, defining strncat, strncpy, or
   stpncpy as a macro in a system header as some implementations
   do suppresses the warning.

I've added a comma after the suppresses to make it clearer and
checked in revision 1.63.

Martin