Document how to add/replace controller node

All in operations guide
- Modified 2320 to introduce subject and source other files
- redeploy subdirectory includes separate files for the actions
- Added steps to add/remove controller nodes

Closes-Bug: 1354586

Change-Id: Ic295b8848c297c2604cdae10d216315b75bdd097
Merge "Document how to add/replace controller node"