add example to set default namespace setting

[nkvuong]

Changes

• Add example on how to set default namespace setting, with etag

Tests

• make test run locally
• make fmt applied
• relevant integration tests applied

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 57.70%. Comparing base (19228af) to head (c782091).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #629   +/-   ##
=======================================
  Coverage   57.70%   57.70%           
=======================================
  Files          47       47           
  Lines       32372    32372           
=======================================
  Hits        18679    18679           
  Misses      13693    13693           

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