docs: refine calibnet nomad job

[vvkio]

Summary

• expand Calibnet Nomad example with service registration and restart policy
• document the open ports and service restart behaviour

Testing

• go test ./... (fails: extern/filecoin-ffi/go.mod: no such file or directory)

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https://chatgpt.com/codex/tasks/task_e_687cd97c692483219a8891141e80a633

[github-actions]

All checks have completed

❌ Failed Test / Test (itest-manual_onboarding) [
"ubuntu-latest"
] (pull_request)
❌ Failed Test / Test (itest-sector_import_full) [
"ubuntu-latest"
] (pull_request)
❌ Failed Test / Test (itest-sector_import_simple) [
"ubuntu-latest"
] (pull_request)
❌ Failed Test / Test (itest-sector_pledge) [
"ubuntu-latest"
] (pull_request)
❌ Failed Test / Test (itest-worker) [
"ubuntu-latest"
] (pull_request)
❌ Failed Test / Test (unit-node) [
"ubuntu-latest"
] (pull_request)
❌ Failed Test / Test (unit-rest) [
"ubuntu-latest"
] (pull_request)
⏭️ Skipped Very Expensive Test / Issue (pull_request)
⏭️ Skipped Very Expensive Test / Test (pull_request)