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

[Julien Fischer]

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