[docs] polish caching docs. (#12684)
* polish caching docs.
* Update docs/source/en/optimization/cache.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
* Update docs/source/en/optimization/cache.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
* up
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Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>