Fix formatting of CHANGELOG.md

Author: Jiri Kadlcik (DHL IT Services)

CHANGELOG.md

@@ -1,13 +1,15 @@
-## 3.0.0
+# 3.0.0
   - Breaking: Updated plugin to use new Java Event APIs
   - relax logstash-core-plugin-api constrains
   - update .travis.yml
 
 # 2.0.4
   - Depend on logstash-core-plugin-api instead of logstash-core, removing the need to mass update plugins on major releases of logstash
+
 # 2.0.3
   - New dependency requirements for logstash-core for the 5.0 release
-## 2.0.0
+
+# 2.0.0
  - Plugins were updated to follow the new shutdown semantic, this mainly allows Logstash to instruct input plugins to terminate gracefully, 
    instead of using Thread.raise on the plugins' threads. Ref: https://github.com/elastic/logstash/pull/3895
  - Dependency on logstash-core update to 2.0