Add a mention of the score change for JSON in the Changelog

This is a fix but I wonder... This looks like the fabled bug that will
break countless integration by being fixed. `--score=y` is the default setting,
and json is probably a prime candidate for automation. Is it reasonable to fix
it and ask everyone to change their option to `-s n`? I'm pretty sure no one
read the pylint's changelog.

Author: Pierre-Sassoulas

ChangeLog

@@ -2,13 +2,14 @@
 Pylint's ChangeLog
 ------------------
 
-* Add check for empty comments
+What's New in Pylint 3.0.0?
+===========================
 
-* Fix minor documentation issue in contribute.rst
+* Fix the score option not being honored when exporting to JSON
 
-* Enums are now required to be named in UPPER_CASE by ``invalid-name``.
+  The default setting was to have a score, but it did not work. Now it will give a score at the end of the json:
 
-  Close #3834
+  Close #3504
 
 
 What's New in Pylint 2.6.1?
@@ -499,6 +500,7 @@ Release date: 2020-04-27
 
   Close #3361
 
+
 What's New in Pylint 2.4.4?
 ===========================
 Release date: 2019-11-13

doc/whatsnew/3.0.rst

@@ -0,0 +1,24 @@
+**************************
+ What's New in Pylint 2.7
+**************************
+
+:Release: 3.0
+:Date: TODO
+
+
+Summary -- Release highlights
+=============================
+
+
+New checkers
+============
+
+
+Other Changes
+=============
+
+*  The score option for JSON export has been fixed
+
+  The default setting is to have a score, but it did not work before.
+  If a score appeared in your json, and you want to go back what you
+  had before, you must change the score option to "--score=n"