[m-rev.] for review: reword reference manual introduction

[Peter Wang]

On Wed, 17 May 2017 16:28:42 +1000 (AEST), Julien Fischer <jfischer at opturion.com> wrote:
> 
> For review by anyone.
> 
> Reword reference manual introduction.
> 
> doc/reference_manual.texi:
>     Reword the introduction: Mercury isn't new, it's over 20 years
>     old at this point.
> 
>     Also, its current developers are no longer at the University
>     of Melbourne.

That's fine.

Peter