Update changelog

Author: martijndwars

CHANGELOG.md

@@ -1,3 +1,9 @@
+# 5.1.0
+
+* Improvement: Add support for [urgency](https://tools.ietf.org/html/rfc8030#section-5.3) & [topic](https://tools.ietf.org/html/rfc8030#section-5.4) (contributed by [email protected]).
+* Maintenance: Upgrade com.beust:jcommander to 1.78.
+* Maintenance: Upgrade org.bitbucket.b\_c:jose4j to 0.7.0.
+
 # 5.0.1
 
 * Bugfix: Only verify the VAPID key pair if the keys are actually present (fixes #73).

RELEASE.md

@@ -1,5 +1,7 @@
 # Release process
 
+0. Update CHANGELOG.md. Include changes to the source code, changes to the version of compile dependencies, etc. Do NOT include changes to the buildscript, version of test dependencies, etc.
+
 1. Update version string in `build.gradle` (1x), `README.md` (2x) to the new (non-SNAPSHOT) version.
 
 ```