fix version name to 1.6.x

Change-Id: Id3e474a8bd77bb474ef1fcbc5df327f7b84db894
diff --git a/doc/source/changelog.rst b/doc/source/changelog.rst
index c3134c5..dccf34f 100644
--- a/doc/source/changelog.rst
+++ b/doc/source/changelog.rst
@@ -5,7 +5,7 @@
 ========= ========== ========================================================
 Version   Date       Changes
 ========= ========== ========================================================
-1.7.0     2018-11-06 * Python code and parser refactoring by a-ovchinnikov
+1.6.0     2018-11-06 * Python code and parser refactoring by a-ovchinnikov
                      * Improvements in yaml_git and mixed setup by Andrew Pickford
                      * Relative paths in class names by Petr Michalec, Martin Polreich and Andrew Pickford
                      * Bug Fixes for recently added features