[WIP] Add some documents

[jstzwj]

[codecov[bot]]

Codecov Report

Merging #72 into master will not change coverage. The diff coverage is n/a.

@@         Coverage Diff          @@
##           master   #72   +/-   ##
====================================
  Coverage       0%    0%           
====================================
  Files          57    57           
  Lines         996   996           
====================================
  Misses        996   996

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