update Bark FA2 docs (#27400)
* update Bark FA2 docs
* update benchmark section
* Update bark.md
* Apply suggestions from code review
Co-authored-by: Sanchit Gandhi <93869735+sanchit-gandhi@users.noreply.github.com>
* rephrase
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Co-authored-by: Sanchit Gandhi <93869735+sanchit-gandhi@users.noreply.github.com>