update changelog

Author: hossam26644

python/CHANGELOG.rst

@@ -12,8 +12,8 @@
   associated with each individual as a numpy array.
   (:user:`benjeffery`, :pr:`3153`)
 
-- Implement thin space separation for thousands in the numbers output for html
-  and text.
+- Use a thin space as the thousands separator in HTML output,
+  and a comma in CLI output.
   (:user:`hossam26644`, :pr:`3167`, :issue:`2951`)
 
 **Fixes**