docs(L1): correct ProtocolVersions owner references and document uncapped iteration

[PelleKrab]

Summary

Comment-only changes to ProtocolVersions. No behavior change — initCodeHash is
unchanged; only sourceCodeHash moves.

Owner references. The NatSpec described the contract as Security Council-controlled,
but access control is enforced via _assertOnlyProxyAdminOwner, so the controlling party
is the ProxyAdmin owner — in production the 2-of-2 multisig. The contract-level @notice
now names that role, and the three owner-gated functions (registerUpgrade,
setMinimumProtocolVersion, setIncidentResponder) read ProxyAdmin owner only instead
of a bare Owner only.

Uncapped iteration. All five loops in this contract iterate _timestamps, so each one
reads as unbounded. Rather than repeat the rationale per loop, it is documented once at the
array declaration: the array only grows via owner-gated registerUpgrade, one entry per
hardfork, so the unbounded iteration poses no gas exhaustion risk.

Test plan

• forge test — full suite passes
• forge fmt --check clean on the changed file
• just semver-lock — refreshed ProtocolVersions sourceCodeHash; initCodeHash
  identical, confirming the change is comment-only

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2