nits: doc update, test cleanup

[Yun-Ting]

No description provided.

[codecov]

Codecov Report

Merging #3520 (584e56b) into main (c1df3a7) will decrease coverage by 0.19%.
The diff coverage is n/a.

❗ Current head 584e56b differs from pull request most recent head a2a8771. Consider uploading reports for the commit a2a8771 to get more accurate results

@@            Coverage Diff             @@
##             main    #3520      +/-   ##
==========================================
- Coverage   86.81%   86.61%   -0.20%     
==========================================
  Files         275      275              
  Lines        9948     9950       +2     
==========================================
- Hits         8636     8618      -18     
- Misses       1312     1332      +20     

Impacted Files	Coverage Δ
...entation/ExportClient/OtlpGrpcTraceExportClient.cs	35.71% <0.00%> (-42.86%)	⬇️
...xporter.OpenTelemetryProtocol/OtlpTraceExporter.cs	36.36% <0.00%> (-40.91%)	⬇️
...metryProtocol/Implementation/ActivityExtensions.cs	91.20% <0.00%> (-3.30%)	⬇️
...etheus.HttpListener/Internal/PrometheusExporter.cs	100.00% <0.00%> (ø)
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	97.65% <0.00%> (+0.78%)	⬆️