Issue #4810's production incident showed the drive timeout knobs are
undiscoverable from symptoms: a listing that outruns the walk budget
gives operators no signal pointing at RUSTFS_DRIVE_* tuning. The knobs
existed only as code constants in crates/config/src/constants/drive.rs
with no operator-facing documentation.
Add docs/operations/drive-timeout-tuning.md covering the per-operation
drive timeout knobs, resolution precedence, the high_latency profile,
and a dedicated section on listing truncation and the walk stall
budget - including the correction that since the stall-budget rework
the foreground listing path is governed by
RUSTFS_DRIVE_WALKDIR_STALL_TIMEOUT_SECS, not the total-timeout knob
the issue suggested. Link the guide from the README.
Ref #4810