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a6610db7 - [Design philosopy] Create official doc (#2140)

[Design philosopy] Create official doc (#2140) * finish more * finish philosophy * Apply suggestions from code review Co-authored-by: YiYi Xu <yixu310@gmail.com> Co-authored-by: Will Berman <wlbberman@gmail.com> --------- Co-authored-by: YiYi Xu <yixu310@gmail.com> Co-authored-by: Will Berman <wlbberman@gmail.com>