[m-dev.] for review: update WORK_IN_PROGRESS file

[Simon Taylor]

> How about the following?
> 
>  | * Mercury is now the official programming language for Melbourne Uni's
>  |   "Aditi" deductive database system.  The Mercury compiler includes
>  |   support for interfacing to Aditi.  However Aditi itself is not yet
>  |   complete and has not yet been made publicly available.

Maybe "A development version of the Mercury compiler includes ...",
so users don't go looking for documentation in the distribution.

Thanks,
Simon.