[docs] Updates for StartWithHost removal

[CodeBlanch]

Relates to #4174

Changes

Documentation updates for the removal of StartWithHost API.

[codecov]

Codecov Report

Merging #4178 (1f7bfc0) into main (74212a2) will decrease coverage by 0.01%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4178      +/-   ##
==========================================
- Coverage   85.50%   85.49%   -0.01%     
==========================================
  Files         291      291              
  Lines       11380    11380              
==========================================
- Hits         9730     9729       -1     
- Misses       1650     1651       +1     

Impacted Files	Coverage Δ
...encyInjectionMetricsServiceCollectionExtensions.cs	100.00% <ø> (ø)
...encyInjectionTracingServiceCollectionExtensions.cs	100.00% <ø> (ø)
...emetry.Api/Internal/OpenTelemetryApiEventSource.cs	76.47% <0.00%> (-5.89%)	⬇️
...ter.ZPages/Implementation/ZPagesActivityTracker.cs	97.14% <0.00%> (-2.86%)	⬇️
...Telemetry/Internal/SelfDiagnosticsEventListener.cs	97.65% <0.00%> (+0.78%)	⬆️
...p/Implementation/HttpInstrumentationEventSource.cs	76.00% <0.00%> (+4.00%)	⬆️