title: Can't figure out how to inject LinkGenerator
body: <p>So I know how to setup my controller so that I can accept a LinkGenerator injected into the controller.  What I can't figure out is how do I inject my controller at startup with a LinkGenerator.</p>
  
  <p>Controller</p>
  
  <pre><code>protected readonly LinkGenerator _linkGenerator;
  
  public SomeController(config config, LinkGenerator linkGenerator)
  {
          config = Config;
          _linkGenerator = linkGenerator;
  }
  </code></pre>
  
  <p>StartUp - ConfigureServices</p>
  
  <pre><code>Controllers.SomeController someController = new 
  Controllers.SomeController(config, linkGenerator); //how do I get an 
  instance of link generator here.
  </code></pre>
  
  <p>services.AddSingleton(someController);</p>
  
  <p>I tried this in the Configure method of startup, but ConfigureServices runs before Configure</p>
  
  <pre><code>app.Use(async (context, next) =&gt;
  {
       linkGenerator = context.RequestServices.GetService&lt;LinkGenerator&gt;();
  });
  </code></pre>
  
  <p>What am I missing?</p>