add CHANGELOG to ease the release process

Author: ziirish

CHANGELOG.rst

@@ -0,0 +1,22 @@
+Changelog
+=========
+
+.. currentmodule:: flask_restx
+
+Current
+-------
+
+- Use github actions instead of Travis (:pr:`18`)
+- Register nested model wildcard fields in docs (:pr:`24`)
+- Pin werkzeug version to <=0.16.1 due to incompatibilities with version 1.0.0 (:pr:`39`)
+
+0.1.0 (2020-01-21)
+------------------
+
+- Ensure that exceptions raised in error handler, including programming errors, are logged
+- Import the ABCs from 'collections.abc' instead of 'collections' by default as it is deprecated since Python3.7, and in 3.8 it will stop working. Python2.7 is still supported though.
+- Fix illegal characters in JSON references to model names
+- Support ``envelope`` parameter in Swagger documentation
+- Fix wildcard support for fields.Nested and fields.List
+- Api/Namespace individual loggers
+- First flask-restx release