Describe how to set the Owin middleware options in code

Fixes #654

doc/OwinMiddleware.md

@@ -6,18 +6,29 @@ authentication pipeline and is compatible with ASP.NET Identity. Kentor
 AuthServices provides external login in the same way as the built in
 Google, Facebook and Twitter providers.
 
-To use the Kentor AuthServices middleware, it need to be configured in
+To use the Kentor AuthServices middleware, it needs to be configured in
 `Startup.Auth.Cs`.
 
     app.UseKentorAuthServicesAuthentication(new KentorAuthServicesAuthenticationOptions());
 
-The options class only contains the owin specific configuration (such as the 
+The options class only contains the Owin-specific configuration (such as the 
 name used to identify the login provider). The rest of the configuration is
 read from the web.config/app.config and [configured in the same way](Configuration.md) 
 as when using the http module or the MVC controller.
 
+If you would like to provide the AuthServices-related configuration in code, specify `false` for
+the `loadConfiguration` constructor parameter and then build the options based on your own
+logic. For example:
+
+    var myAuthServicesOptions = new KentorAuthServicesAuthenticationOptions(false)
+    // more logic to set SPOptions, etc.
+    app.UseKentorAuthServicesAuthentication(myAuthServicesOptions);
+
+You can see a full example of this in the **SampleOwinApplication** project included in the
+source code. See the [Startup.Auth.cs file](https://github.com/KentorIT/authservices/blob/master/SampleOwinApplication/App_Start/Startup.Auth.cs)
+
 ##Selecting Idp
-An Owin based application issues a AuthenticationResponseChallenge to ask the
+An Owin-based application issues an AuthenticationResponseChallenge to ask the
 middleware to begin the authentication procedure. In that challenge, there is
 a properties dictionary. To use a specified idp, the entity id of the idp should
 be entered in that dictionary under the key "idp".