B2 SDK docs: file-retention examples call update_file_legal_hold with the wrong setting type

[ffumero2003]

Description

The Quick Start guide passes a FileRetentionSetting to B2Api.update_file_legal_hold. The documented equivalent calls in the direct-file section repeat the same mistake. Retention settings belong to update_file_retention.

Steps to reproduce

b2_api.update_file_legal_hold(
    file_id,
    file_name,
    FileRetentionSetting(RetentionMode.GOVERNANCE, retain_until),
)

Expected behavior

The guide should call update_file_legal_hold(..., LegalHold.ON) for legal holds and update_file_retention(..., FileRetentionSetting(...)) for retention.

Actual behavior

The guide sends a retention object to a method whose public signature requires a LegalHold value.

Environment

• Python version: Any supported version
• b2sdk version: master at f3ab7b71
• OS: Any

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