Add performance_tuning to jetty/tutorials

[ammaarrahmed]

New feature

Part of #673

Summary

Add a Jetty performance tuning guide with a short set of practical tips for improving simulation performance and real-time factor.

This PR keeps the first pass small:

• adds a new performance_tuning.md page under Jetty tutorials
• links it from the Jetty tutorials landing page and sidebar
• focuses on documented tuning knobs such as physics step size, sensor update rates, simpler collision / visual models, rendering settings, and GPU setup
• links out to existing docs or external references for more specialized options instead of trying to cover everything in one page

Checklist

• Signed all commits for DCO
• Added a screen capture or video to the PR description that demonstrates the feature
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• Updated Bazel files (if adding new files). Created an issue otherwise.
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Generated-by: copilot for .md content

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[Copilot]

Pull request overview

Adds a new Jetty documentation page that guides users through practical steps to improve simulation performance / real-time factor, and exposes it through the tutorials landing page and sidebar.

Changes:

• Added a new jetty/performance_tuning.md performance tuning guide.
• Linked the new guide from jetty/tutorials.md.
• Registered the new page in the Jetty docs sidebar via jetty/index.yaml.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
jetty/tutorials.md	Adds a “Performance tuning” entry under Basics tutorials.
jetty/performance_tuning.md	New tutorial page describing measurement and common tuning knobs, plus links to advanced/external options.
jetty/index.yaml	Adds the new page to the tutorials section so it appears in the docs sidebar.

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[ammaarrahmed]

Hey @azeey , sorry to nudge , I would really appreciate some feedback on this PR and what could I further do to get this merged , please let me know, thanks.