builder.Services.AddHttpClient DefaultName not clear

### Type of issue

Missing information

### Description

[Enter feedback here]

The way DefaultName works it's not explained at all, please add a small one-two liner example into the page on how this works and needs to be implemented

### Page URL

https://learn.microsoft.com/en-us/dotnet/api/microsoft.extensions.dependencyinjection.httpclientfactoryservicecollectionextensions.addhttpclient?view=net-9.0-pp&viewFallbackFrom=net-8.0#microsoft-extensions-dependencyinjection-httpclientfactoryservicecollectionextensions-addhttpclient(microsoft-extensions-dependencyinjection-iservicecollection-system-string-system-action((system-iserviceprovider-system-net-http-httpclient)))

### Content source URL

https://github.com/dotnet/dotnet-api-docs/blob/main/xml/Microsoft.Extensions.DependencyInjection/HttpClientFactoryServiceCollectionExtensions.xml

### Document Version Independent Id

8d1c33d9-0665-bfa5-e6a2-363e28a7480a

### Article author

@dotnet-bot