Redfish Phase 5: rewrite redfish.md + example to the real flow

[wrkode]

Part of #4109 (Phase 5). Owner: tech-writer.

Documentation honest to the real URL-pull flow.

Scope

• Rewrite redfish.md and examples/redfish/deploy.sh to the actual flow: discover → InsertMedia (URL-pull) → boot override → Reset+ResetType → Task poll → session teardown.
• Document the ISO-serving model (D4): --image-url default, server tokenized serve, --serve/--redfish-serve-* flags, and the HTTP-on-trusted-L2 posture + opt-in --redfish-serve-tls.
• Document creds hygiene (--password-file/stdin), --verify-ssl default, and the BMC-cred-at-rest encryption.
• Stop documenting aspirational flows as if they work.

Closes catalogue items

#12.