8.11.2 is no longer supported

[Dmitri Maziuk]

Just F devs Y, solrconfig.xml copied from default configset still has 
"<jmx />" in it, and generates the warning on startup. No big deal but 
should probably be cleaned up if it's still there in 9+ -- and if 
there's ever another 8.x release.

(I'm rebuilding our lose2012R2 hosts & spinning up new Solr instances, 
so I get to see startup messages.)

Dima