v19.2.0
doc/start: add links to Beginner's Guide
doc/start/ceph.conf: trim the sample ceph.conf file
docs: Add information about OpenNebula integration
doc/start: update mailing list links
doc/start: fix wording & syntax
doc/start: remove "intro.rst"
doc/start/os-recommendations: remove 16.2.z support for CentOS 7
doc: remove references to ceph-deploy