Update changelog.rst

Author: hriener

docs/changelog.rst

@@ -1,9 +1,12 @@
 Change Log
 ==========
 
-v0.2 (not yet released)
+v0.3 (not yet released)
 -----------------------
 
+v0.2 (February 16, 2021)
+------------------------
+
 * Network interface:
     - `is_function` `#148 <https://github.com/lsils/mockturtle/pull/148>`_
     - `is_nary_and`, `is_nary_or`, `is_nary_xor` `#304 <https://github.com/lsils/mockturtle/pull/304>`_