add 1.18.0 blog post

Change-Id: Id8d78844a6b9a8389d87c6a63820b04c98ef49c3
Reviewed-on: http://gerrit.cloudera.org:8080/23151
Reviewed-by: Zoltan Chovan <zchovan@cloudera.com>
Reviewed-by: Alexey Serbin <alexey@apache.org>
Reviewed-by: Marton Greber <greber.mx@gmail.com>
Tested-by: Abhishek Chennaka <achennaka@cloudera.com>
1 file changed