[m-rev.] diff: update samples/README.md

[Julien Fischer]

Update samples/README.md.

samples/README.md:
      Include the recently C# interface subdirectory.

Julien.

diff --git a/samples/README.md b/samples/README.md
index c656228..a112b13 100644
--- a/samples/README.md
+++ b/samples/README.md
@@ -64,6 +64,9 @@ Mercury programs:
  * [c_interface](c_interface) -- This directory contains some examples of mixed
    Mercury/C/C++/Fortran programs using the C interface.

+* [csharp_interface](csharp_interface) -- This directory contains some
+  examples of mixed Mercury/C# programs using the foreign language interface.
+
  * [java_interface](java_interface) -- This directory contains some examples of
    mixed Mercury/Java programs using the foreign language interface.