Stackless issues #135, #136: update changelog.txt

(cherry picked from commit f845a0f)

Author: Anselm Kruis

Stackless/changelog.txt

@@ -15,6 +15,12 @@ What's New in Stackless 3.X.X?
 - https://github.com/stackless-dev/stackless/issues/138
   Correctly propose Stackless calls for C-functions.
 
+- https://github.com/stackless-dev/stackless/issues/136
+  Replace 'xrange' with 'range' in *.py. Python 3 has no xrange.
+
+- https://github.com/stackless-dev/stackless/issues/135
+  Fix small memory leaks for types with Stackless extensions.
+
 
 What's New in Stackless 3.5.3 and 3.5.4?
 ========================================