Add change log, Update Maven to 3.6.3.

Author: wu-sheng

CHANGES.md

@@ -13,6 +13,7 @@ Release Notes.
 * Bump up oap to the 10.3-dev.latest(dc8740d4757b35374283c4850a9a080e40f0eb79) in e2e.
 * Bump up cli to the 0.15.0-dev.latest(77b4c49e89c9c000278f44e62729d534f2ec842e) in e2e.
 * Bump up apache parent pom to v35.
+* Update Maven to 3.6.3.
 
 All issues and pull requests are [here](https://github.com/apache/skywalking/milestone/242?closed=1)