[m-rev.] for review: add link to sample from README.md

[Julien Fischer]

I am going to commit this one; I will deal with any review comments 
post-commit.

Julien.

On Sat, 1 Jan 2022, Julien Fischer wrote:

>
> For review by anyone.
>
> --------------------
>
> Add link to samples from README.md.
>
> README.md:
>     As above.
>
> Julien.
>
> diff --git a/README.md b/README.md
> index 5bb39d7..d7e279a 100644
> --- a/README.md
> +++ b/README.md
> @@ -10,6 +10,9 @@ More information is available on the
>  in other README files in the source code repository, and in the
>  [documentation](http://www.mercurylang.org/documentation/documentation.html).
>
> +Small sample programs written in Mercury can be found in the 
> [samples](samples)
> +directory of the source code repository.
> +
>  ## README files
>
> The Mercury compiler has a number of different
>
>