chore: remove YAML maxDepth

[RomneyDa]

Description

Deprecated for YAML, looking to replace with maxPages, allow/block list, etc.

Followup to #5958

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Summary by cubic

Removed the deprecated maxDepth option from YAML config and related documentation. This prepares for future config changes using maxPages and allow/block lists.

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[cubic-dev-ai]

cubic reviewed 4 files and found no issues. Review PR in cubic.dev.