[doc] add security model doc and update contributors

[tomsun28]

What's changed?

add security model doc, @zqr10159 ptal

Checklist

• I have read the Contributing Guide
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

Add or update API

• I have added the necessary e2e tests and all cases have passed.

[tomsun28]

refer https://cwiki.apache.org/confluence/display/SECURITY/Documenting+your+security+model

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 32.18%. Comparing base (1fe70a6) to head (445ff96).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2846      +/-   ##
============================================
- Coverage     32.19%   32.18%   -0.01%     
  Complexity     1914     1914              
============================================
  Files           507      507              
  Lines         18663    18663              
  Branches       2273     2273              
============================================
- Hits           6008     6007       -1     
- Misses        11949    11950       +1     
  Partials        706      706              

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[zqr10159]

lgtm