Extend example to include support for Lifetime Startup Messages

[snakefoot]

We have already recognized it is important to perform logging of Lifetime Startup Messages:

https://github.com/NLog/NLog.Web/wiki/Hosting-Lifetime-Startup-Messages

But the example code is this:

      .ConfigureLogging(logging =>
      {
          logging.ClearProviders();   // Removes the default console-logger
          logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
      })

And the Nlog.config contains these rules:

  <rules>
    <!--All logs, including from Microsoft-->
    <logger name="*" minlevel="Trace" writeTo="allfile" />

    <!--Skip non-critical Microsoft logs and so log only own logs-->
    <logger name="Microsoft.*" maxlevel="Info" final="true" /> <!-- BlackHole without writeTo -->
    <logger name="*" minlevel="Trace" writeTo="ownFile-web" />
  </rules>

Maybe ConsoleTarget with Microsoft-Logger should be added to NLog.config in the tutorial, so Lifetime Startup Messages will work out of the box with NLog.

[304NotModified]

Good idea :)