SOLR-6323: Updated CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1640259 13f79535-47bb-0310-9956-ffa450edef68
SOLR-6684: Updated CHANGES.txt

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1640261 13f79535-47bb-0310-9956-ffa450edef68