update change log

docs/sphinx/source/changelog/pending.rst

@@ -1,18 +1,26 @@
-********************************
+*******
 pending
-********************************
+*******
+
+Breaking changes
+------------
+These changes have the potential to change answers in existing scripts
+when compared with older versions of RdTools
+* Use the pvlib method for clear sky detection by default in
+:py:func:`~rdtools.analysis_chains.TrendAnalysis` (:pull:'412')
 
 Enhancements
 ------------
-* added a new wrapper function for clearsky filters
+* Added a new wrapper function for clearsky filters (:pull:'412')
 
 Bug fixes
 ---------
 * tbd
 
 Requirements
 ------------
-* tbd
+* Specified versions in ``requirements.txt`` and ``docs/notebook_requirements.txt``
+have been updated (:pull:'412')
 
 Contributors
 ------------