Create alerts & runbooks covering major Coder architectural components, deployment environment

[dannykopping]

• [x] Failure to connect to database
• [ ] No coderd replicas up
• [ ] No provisioner replicas up
• [x] Pod OOMs (special handling for workspaces?)
• [ ] Resource usage exceeding margin
  • [x] CPU
  • [x] Memory
  • [ ] Disk (requires metrics-server to be installed)
  • [x] License seats
• [ ] Workspace build failures
• [x] Pod restarts
• [ ] Workspace proxy failures (coderd_proxyhealth_health_check_results)
  • add proxy name as label
  • add error code as label, use to link to documentation