[VDR][v0.6.0] Docs stale vs. shipped code

[anwithk]

Theme issue grouping v0.6.0-cycle VDR findings: Docs stale vs. shipped code.

Finding	Severity	Summary
DOC-5be47580	🟠 high	Reverify tutorial's Hydra override targets a config key that does not exist
DOC-2387547e	🟠 high	gym list benchmarks is documented with columns the command no longer prints

Child issues are linked as sub-issues below.

_{DX review Gym-1-20260821203248 — incremental from v0.5.0 to fa0d25158. Parent tracker #2214.}