* rolling upgrade order change to bring coordinator and overlord together
* mentioned merged Coordinator-Overlord in upgrade order doc
* revert autoscaling doc change
* auto scaling doc fix
1. Clarify what "Indexing Service / Realtime" means
2. Add info about restore-based middle manager rolling restarts
3. Add info about what happens in middle manager updates
4. More consistent capitalization and spelling of node types
Himanshu
Gian Merlino