dotnet new webapi

builder.Services.AddSwaggerGen(
    swaggerGenConfiguration =>
    {
        var assembly = System
            .Reflection
            .Assembly
            .GetExecutingAssembly()
            ;
        var assemblyName = assembly
            .GetName()
            .Name
            ;
		var xmlFile = $"{assemblyName}.xml";
		var xmlPath = Path.Combine(
			AppContext.BaseDirectory,
			xmlFile
		);

        swaggerGenConfiguration.IncludeXmlComments(
            xmlPath
        );
    }
);

/// <summary>
///     This is my XML documentation comment!
/// </summary>

[HttpGet("GetWeatherForecast")]

/// <summary>
///     Extends <see cref="WeatherForecastController" />.
/// </summary>
public class WeatherForecastController2
    : WeatherForecastController
{
    /// <summary>
    ///     Create a new instance.
    /// </summary>
    /// <param name="logger">
    ///     The logger.
    /// </param>
	public WeatherForecastController2(
		ILogger<WeatherForecastController> logger
	)
		: base(
			logger
		)
	{

	}

	/// <inheritdoc />
	public override IEnumerable<WeatherForecast> Get()
		=> base.Get();
}

dotnet run

/// <summary>
///     This is my XML documentation comment without inheriting from the base type!
/// </summary>

dotnet run