[docs-traces] Added version info to the OTEL_TRACES_SAMPLER doc

[CodeBlanch]

Follow-up to #5448

Changes

• Adds release version info to the OTEL_TRACES_SAMPLER doc.
• Improve the code ever so slightly.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.51%. Comparing base (6250307) to head (2ff0358).
Report is 154 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5492      +/-   ##
==========================================
+ Coverage   83.38%   85.51%   +2.12%     
==========================================
  Files         297      289       -8     
  Lines       12531    12591      +60     
==========================================
+ Hits        10449    10767     +318     
+ Misses       2082     1824     -258     

Flag	Coverage Δ
unittests	?
unittests-Solution-Experimental	85.50% <100.00%> (?)
unittests-Solution-Stable	85.26% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
src/OpenTelemetry/Trace/TracerProviderSdk.cs	99.36% <100.00%> (+0.08%)	⬆️

... and 64 files with indirect coverage changes