Write documentation for new roster lifecycle (Audience: DevOps and Solo developers)

**Background**

The changes required for the implementation of this epic affect DevOps and SOLO Dynamic Address Book code. Prior to this epic, both DevOps and SOLO would need to move `config.txt` and the public gossip keys from where they were written on a freeze upgrade transaction to where the files are expected at startup. Since we are no longer writing `config.txt` and public gossip keys, the code expecting to see and move them needs to be modified to tolerate their absence.

Write documentation on the new roster lifecycle and the new files for genesis and network override. This will be used by DevOps and SOLO to adjust their behavior in DAB scenarios.

**Acceptance Criteria**

* Documentation is signed off by the team as being accurate and complete.

**Dependencies**

All integration tickets are complete, which would entail code completion.

Start by reviewing the completed integration tickets and the current roster lifecycle, including the genesis and network override files mentioned in the issue. Document the new lifecycle and file behavior for DevOps and SOLO DAB scenarios; the work is done when the team signs off that the documentation is accurate and complete.

Written by the indexing model from the issue text.