[WIP] Doc: Translate "Additional Notes" and "Implementation Details" subsections of arch/cache/cache-arch

`cache-arch.en.rst` の "Additional Notes" , "Implementation Details" 節を翻訳します。
原文: https://trafficserver.readthedocs.org/en/latest/arch/cache/cache-arch.en.html#additional-notes

WIP につき、まだマージしないでください。