cleanup(bigquery): fix column name in usa_names rustdoc examples

[dbolduc]

Fixes #6882

[gemini-code-assist]

Code Review

This pull request updates the documentation examples in src/bigquery/src/lib.rs and src/bigquery/src/query/client.rs to use the field name 'number' instead of 'count' in the SQL queries, struct definitions, and output printing. There are no review comments, and I have no feedback to provide.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.17%. Comparing base (2edb4a6) to head (a74991b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6883   +/-   ##
=======================================
  Coverage   97.17%   97.17%           
=======================================
  Files         326      326           
  Lines      110145   110145           
=======================================
+ Hits       107034   107037    +3     
+ Misses       3111     3108    -3     

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.