From the README:

If your project uses .NET SDK 8+ and is hosted by the above providers it does not need to reference any Source Link packages or set any build properties.

Otherwise, you can enable Source Link experience in your project by setting a few properties and adding a PackageReference to a Source Link package specific to the provider:

<Project>
 <PropertyGroup>
    <!-- Optional: Publish the repository URL in the built .nupkg (in the NuSpec <Repository> element) -->
    <PublishRepositoryUrl>true</PublishRepositoryUrl>
 
    <!-- Optional: Embed source files that are not tracked by the source control manager in the PDB -->
    <EmbedUntrackedSources>true</EmbedUntrackedSources>
  </PropertyGroup>
  <ItemGroup>
    <!-- Add PackageReference specific for your source control provider (see below) --> 
  </ItemGroup>
</Project>

Both NuGet Package Explorer and the binlog tell me that EmbedUntrackedSources is set automatically, but PublishRepositoryUrl is not. I do see that GenerateRepositoryUrlAttribute = true is set automatically.

Without explicit PublishRepositoryUrl:

With explicit PublishRepositoryUrl:

I guess this is simply a documentation error, and not a bug in the SDK?