docs(cli): align hermes update flags

[TonyPepeBear]

Summary

Align the hermes update section in the CLI Commands Reference with the current CLI parser.

The docs previously listed --restart-gateway, but hermes update --help does not register that flag. Running the documented command fails with:

hermes: error: unrecognized arguments: --restart-gateway

What changed

• Remove the unsupported --restart-gateway flag from the hermes update synopsis
• Document the currently supported update flags: --gateway, --check, --no-backup, --backup, and --yes / -y
• Clarify that --gateway is the internal messaging /update IPC mode, not a gateway restart flag
• Document the current automatic gateway restart behavior after a successful update

Test plan

Docs-only change.

Locally verified:

git diff --check
hermes update --help

[TonyPepeBear]

Closing this because the relevant docs changes have already landed on main via ee0a9bf and a2d3cff. Thanks!