Migrate changelog to markdown and update

Changes.rst → CHANGELOG.md

-Changes for v0.2.0 (2020-08-29)
-===============================
+# CHANGELOG
 
--  Implemented support for (created) and (expires) special headers (#14)
+## Changes for v0.3.0 (2022-04-03)
+
+- Make created field optional on verification
+- Do not add created field if algorithm is rsa, hmac or ecdsa
+- Set correct Scheme for HTTPSignatureHeaderAuth
+- Remove python2 compatibility code
+- Fix usage of class methods
 
+## Changes for v0.2.0 (2020-08-29)
+
+-  Implemented support for (created) and (expires) special headers (#14)
 -  Raise informative error when unable to compute body digest
 
-Changes for v0.1.0 (2018-11-05)
-===============================
+## Changes for v0.1.0 (2018-11-05)
 
 -  Support using a Signature header instead of Authorization header.
-
 -  Add RSA512 algorithm.
 
-Changes for v0.0.3 (2017-09-19)
-===============================
+## Changes for v0.0.3 (2017-09-19)
 
 -  HTTPSignatureAuth.verify: Rely only on request.url, not path\_url
-
 -  Docs improvements (PR #1 from kennethreitz/patch-1)
 
-Changes for v0.0.2 (2017-08-22)
-===============================
+## Changes for v0.0.2 (2017-08-22)
 
 -  Require key ID
-
 -  Make verify a class method for clarity
 
-Changes for v0.0.1 (2017-08-22)
-===============================
+## Changes for v0.0.1 (2017-08-22)
 
 Initial release.