Release a 6.6.1

[Varun Thacker]

>From the change log of 6.7 / 7.0 and 7.1 the total count of bug fixes under
lucene and solr are

Lucene : 7
Solr : 61


I'd be happy to volunteer as a release manager for a bug fix 6.6.1 release
if others in the community think it's a good idea