feat(main): fix readme

[cuisongliu]

This pull request includes changes to the configuration files to add broker replicas to the setup. The most important changes are in the README.md and config/samples/infra_v1beta1_automq.yaml files.

Configuration updates:

• README.md: Added a broker section with replicas set to 3.
• config/samples/infra_v1beta1_automq.yaml: Added a broker section with replicas set to 3.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.31%. Comparing base (1804723) to head (c68f92c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #62   +/-   ##
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  Coverage   36.31%   36.31%           
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  Files           5        5           
  Lines         413      413           
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  Hits          150      150           
  Misses        240      240           
  Partials       23       23           

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