Date format fix in changelog

Signed-off-by: martin f. krafft <madduck@madduck.net>
diff --git a/doc/source/changelog.rst b/doc/source/changelog.rst
index abb4bef..57cc0e9 100644
--- a/doc/source/changelog.rst
+++ b/doc/source/changelog.rst
@@ -5,7 +5,7 @@
 ========= ========== ========================================================
 Version   Date       Changes
 ========= ========== ========================================================
-1.2       2013.12.10 * Introduce class mappings (see :doc:`operations`)
+1.2       2013-12-10 * Introduce class mappings (see :doc:`operations`)
                        (closes: #5)
                      * Fix parameter interpolation across merged lists
                        (closes: #13).