Add remaining docs to Microsoft.Extensions.Http

[CarnaViire]

Contributes to dotnet/runtime#43916

[opbld31]

Docs Build status updates of commit eb5e8df:

✅ Validation status: passed

File	Status	Preview URL	Details
xml/Microsoft.Extensions.Http/HttpClientFactoryOptions.xml	✅Succeeded	View
xml/Microsoft.Extensions.Http/HttpMessageHandlerBuilder.xml	✅Succeeded	View
xml/Microsoft.Extensions.Http/PolicyHttpMessageHandler.xml	✅Succeeded	View
xml/ns-Microsoft.Extensions.Http.Logging.xml	✅Succeeded	View
xml/ns-Microsoft.Extensions.Http.xml	✅Succeeded	View

For more details, please refer to the build report.

Note: Broken links written as relative paths are included in the above build report. For broken links written as absolute paths or external URLs, see the broken link report.

For any questions, please:

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[gewarren]

LGTM