New Features in 6.0 section for Release Notes

Added features listed in the Roadmap
Features are grouped as included in the 6.0TP release
and under development for 6.0 GA.

I did not include the upstream merge of Puppet modules;
this seems more like a process improvement than a product
improvement but perhaps I misunderstand.

I removed the update/upgrade issues for Tech Preview

Change-Id: Ib1081e45f8e79015d0bd1c5742abf146e66c685f