[Doc] Link to RFC for pooling optimizations

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Purpose

Update Pooling Model docs to point to #21796

cc @maxdebayser @Isotr0py

Test Plan

Test Result

(Optional) Documentation Update

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[gemini-code-assist]

Code Review

This pull request updates the documentation for pooling models to include a link to an RFC about future optimizations. The change is straightforward. I've suggested retaining the warning about current performance and feature limitations to ensure users have accurate expectations.