[doc] add baota extern install doc

[tomsun28]

What's changed?

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.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 31.90%. Comparing base (4f18c2c) to head (8bf7a55).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2768      +/-   ##
============================================
+ Coverage     31.88%   31.90%   +0.01%     
- Complexity     1706     1707       +1     
============================================
  Files           411      411              
  Lines         16584    16584              
  Branches       2142     2142              
============================================
+ Hits           5288     5291       +3     
+ Misses        10655    10651       -4     
- Partials        641      642       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[yuluo-yx]

LGTM