docs: spartan network user guide

[just-mitch]

As a technical writer, I want to create comprehensive documentation so that developers and users can effectively work with and join the network.

- [ ] Write user guide for deploying networks with the Helm chart
- [ ] Create developer documentation for extending the chart
- [ ] Document process for joining the Spartan network
- [ ] Create runbooks for common operational tasks
- [ ] Set up a process for keeping documentation up-to-date