Update shard tensor ring attention example

[coreyjadams]

Now, the generation script will use the expected default results directory.

PhysicsNeMo Pull Request

Description

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.
• The CHANGELOG.md is up to date with these changes.
• An issue is linked to this pull request.
• If I am implementing a new model or modifying any existing model, I have followed the Models Implementation Coding Standards.

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[greptile-apps]

Greptile Summary

This PR updates the ring-attention benchmark script to write JSON results by default (opt-out via --print-only) into an auto-named file under a results/ directory that is resolved relative to the script itself, replacing the previous opt-in --output_file argument. The README is updated to document the new flags.

• --output_file → --results_dir + auto-naming: filenames now encode topology, mode, dtype, and sequence length to match the regex expected by plot_scaling_results.py.
• Default behaviour flipped: results are saved automatically unless --print-only is passed; all file I/O is correctly guarded inside if dm.rank == 0: to avoid duplicate writes in distributed runs.

Important Files Changed

Filename	Overview
examples/minimal/ShardTensorExamples/6_ring_attention/benchmark_sharded_attention.py	Replaces --output_file (opt-in, manual path) with --results_dir (opt-out, auto-named output); adds --print-only flag; all file I/O remains correctly guarded under dm.rank == 0.
examples/minimal/ShardTensorExamples/6_ring_attention/README.md	Updates argument table and adds description for the new --results_dir and --print-only flags; minor documentation discrepancy about default path relativity.

_{Reviews (1): Last reviewed commit: "Update shard tensor ring attention to us..." | Re-trigger Greptile}

[negin513]

Tiny consistency nitpick: every other flag in this file is underscore-cased (--results_dir, ...) and --print-only is the only one that is - based. Would it make sense to use --print_only instead?

[negin513]

LGTM! Just a few very minor comments inline.