Update changelog for 0.20.0

Author: cducrest

CHANGELOG.rst

@@ -3,6 +3,9 @@ Change Log
 ==========
 `unreleased`_
 -------------------------------
+
+`0.20.0`_ (2020-02-12)
+-------------------------------
 - Updated: Use ethindex to update `is_frozen` status of network graphs instead of filters
   requires ethindex>=0.3.5
 
@@ -266,4 +269,5 @@ Change Log
 .. _0.17.1: https://github.com/trustlines-protocol/relay/compare/0.17.0...0.17.1
 .. _0.18.0: https://github.com/trustlines-protocol/relay/compare/0.17.1...0.18.0
 .. _0.19.0: https://github.com/trustlines-protocol/relay/compare/0.18.0...0.19.0
-.. _unreleased: https://github.com/trustlines-protocol/relay/compare/0.19.0...master
+.. _0.20.0: https://github.com/trustlines-protocol/relay/compare/0.19.0...0.20.0
+.. _unreleased: https://github.com/trustlines-protocol/relay/compare/0.20.0...master