[Doc] Add benckmark_moe doc

[jeejeelee]

Purpose

Part of #24112

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request updates the documentation for Fused MoE Triton Kernel Configurations by renaming the README file to README.md and adding markdown structure. While the formatting improvements are a good step, I've noticed an incomplete section has been added which should be addressed.

[gemini-code-assist]

The new section ### Tune MoE kernel is empty. This could be confusing for readers and makes the documentation feel incomplete. Please either add the relevant content for tuning the MoE kernel or remove this section if it's not yet ready.