docs: fix performance benchmark script paths

[JJJ-NONAME]

Summary

• Fix the performance benchmark README command to use the script's actual docs/benchmarks/performance/ path.
• Keep the script's own example consistent with that path.

Closes #1446.

Verification

• git diff --check
• Confirmed both documented paths resolve to the tracked script.
• make pr-ready was attempted; the repository's POSIX-only syscall tests and shell steps cannot run on this Windows host.

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[santoshkumarradha]

Hey, thanks for the PR. Could you sign the CLA when you get a chance so we can review it?

[santoshkumarradha]

The two proposed path corrections are byte-identical to the incorporated #1498 changes, which also include a regression test. This is duplicate coverage, not a separate source-head merge. Superseded by #1632. The aggregate remains draft pending the remaining batch and final checks; this does not indicate a merge into dev.

[santoshkumarradha]

Reopening: the second consolidation is now restricted to Santosh-authored PRs, so this contributor PR remains outside #1632. The earlier consolidation-related closure no longer applies.