title: reading appconfig file for serilog
body: <p>I have <code>Logger.cs</code> class where I am initializing serilog settings as follows:</p>
  
  <pre><code>_logger = new LoggerConfiguration()
                  .ReadFrom.AppSettings()
                  .MinimumLevel.Debug()
                  .WriteTo.File(_filepath, restrictedToMinimumLevel: LogEventLevel.Debug, shared: true, rollOnFileSizeLimit: true)
                  .CreateLogger();
  </code></pre>
  
  <p>I want to read the size of the file from app.config file. 
  I have the app.config file as below</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8" ?&gt;
  &lt;configuration&gt;
    &lt;appSettings&gt;
      &lt;add key="serilog:using:File" value="Serilog.Sinks.File" /&gt;
      &lt;add key="serilog:write-to:File.fileSizeLimitBytes" value="2000" /&gt;
    &lt;/appSettings&gt;
  &lt;/configuration&gt;
  </code></pre>
  
  <p>But looks like <code>appsettings</code> is not read at all. because I can see more than 2kb file getting generated.
  What I have missed here?</p>
  
  <p>How my logger class will read from <code>app.config</code> file, have I missed any settings in assemblyinfo class?</p>