add 040 whatsnew

Author: wholmgren

docs/sphinx/source/whatsnew.rst

@@ -6,6 +6,7 @@ What's New
 
 These are new features and improvements of note in each release.
 
+.. include:: whatsnew/v0.4.0.txt
 .. include:: whatsnew/v0.3.3.txt
 .. include:: whatsnew/v0.3.2.txt
 .. include:: whatsnew/v0.3.1.txt

docs/sphinx/source/whatsnew/v0.4.0.txt

@@ -0,0 +1,23 @@
+.. _whatsnew_0400:
+
+v0.4.0 (June xx, 2016)
+-----------------------
+
+This is a major release from 0.3.3.
+We recommend that all users upgrade to this version.
+
+Enhancements
+~~~~~~~~~~~~
+
+* Splits ``ModelChain`` into a ``SingleDiode`` chain and a ``SAPM`` chain.
+  (:issue:`151`)
+
+
+Bug fixes
+~~~~~~~~~
+
+
+Contributors
+~~~~~~~~~~~~
+
+* Will Holmgren