[wwwdocs] Document Nios II changes for GCC 8

[Gerald Pfeifer]

On Sun, 29 Oct 2017, Sandra Loosemore wrote:
> I've checked in this patch to document my recent flurry of Nios II 
> patches in the release notes for GCC 8.

Thank you!

>     The Nios II back end has been improved to generate better-optimized
>     code.  Changes include switching to LRA, more accurate cost models,
>     and more compact code for addressing static variables.

"better-optimized" with a dash, isn't that a bit German where we 
have words like Zugführerkontrollleuchtenschalter? ;-)

LRA has not been used inthat note so far.  Would it be appropriate
to say something like "LRA (a new local register allocator)" instead?

(This is what we do in gcc-7/changes.html the first time LRA is
referred to.)

>     New command-line options <code>-mgprel-sec=</code> and
>     <code>-mr0rel-sec=</code> have been added.

Would it make sense to hint what these options are about (which
areas they cover)?

Gerald