Convert CHANGELOG to rst format #47

Signed-off-by: Steven Esser <sesser@nexb.com>

CHANGELOG.rst

@@ -0,0 +1,41 @@
+Changelog
+=========
+All notable changes to this project will be documented in this file.
+
+The format is based on `Keep a
+Changelog <https://keepachangelog.com/en/1.0.0/>`__
+
+[Unreleased]
+------------
+
+[1.2] - 2019-11-14
+------------------
+Added
+~~~~~
+-  Add ability to render WITH expression wrapped in parenthesis
+
+Fixes
+~~~~~
+-  Fix anomalous backslashes in strings
+
+Changed
+~~~~~~~
+-  Update the thirdparty directory structure.
+
+[1.0] - 2019-10-16
+------------------
+Added
+~~~~~
+-  New version of boolean.py library
+-  Add ability to leave license expressions unsorted when simplifying
+
+Changed
+~~~~~~~
+-  updated travis CI settings
+
+[0.999] - 2019-04-29
+--------------------
+-  Initial release
+-  license-expression is small utility library to parse, compare and
+   simplify and normalize license expressions.
+