Update notification links (#225)

Author: vaheeshta

Samples/Notifications/Push/README.md

@@ -17,7 +17,7 @@ This sample demonstrates:
 * A web API tool (like Postman or fiddler) to send notifications.
    * The Windows App SDK push notifications APIs provides an API to register for and receive notifications from an external app service. The web API tool is used to emulate the external app service.
 * An Azure AppId for your app.
-   * To obtain an Azure AppId, follow "Configure your app's identity in Azure Active Directory" [here](https://docs.microsoft.com/windows/apps/windows-app-sdk/notifications/push/push-quickstart#configure-your-apps-identity-in-azure-active-directory).
+   * To obtain an Azure AppId, follow "Configure your app's identity in Azure Active Directory" [here](https://docs.microsoft.com/windows/apps/windows-app-sdk/notifications/push-notifications/push-quickstart#configure-your-apps-identity-in-azure-active-directory-aad).
 * Windows 10
 ## Building and running the sample 
 Before building the sample, make sure to set up your environment correctly by following the steps [here](https://docs.microsoft.com/windows/apps/windows-app-sdk/set-up-your-development-environment).
@@ -33,11 +33,13 @@ winrt::guid remoteId{ "00000000-0000-0000-0000-000000000000"};
 
 The sample will display a WNS Channel URI which uniquely identify this app, for this user on this device and thus can be used by other apps (usually a server app) to send notifications to this specific app.
 ## Receiving Notifications
-Follow these [instructions]() to send a notification to the sample. 
+Follow these [instructions](https://docs.microsoft.com/windows/apps/windows-app-sdk/notifications/push-notifications/push-quickstart#send-a-push-notification-to-your-app) to send a notification to the sample. 
    * Leave the sample running to receive notifications in the foreground.
    * Close the sample to receive notifications in the background.
 ## Related Links
 - [Windows App SDK](https://docs.microsoft.com/windows/apps/windows-app-sdk/)
-- [Push Notifications Doc](https://docs.microsoft.com/windows/apps/windows-app-sdk/notifications/push/)
+- [Push notifications overview](https://docs.microsoft.com/windows/apps/windows-app-sdk/notifications/push-notifications/)
+- [Quickstart Push notifications in the Windows App SDK](https://docs.microsoft.com/windows/apps/windows-app-sdk/notifications/push-notifications/push-quickstart)
+- [Microsoft.Windows.PushNotifications Namespace](https://docs.microsoft.com/windows/windows-app-sdk/api/winrt/microsoft.windows.pushnotifications)
 ## Common Issues
 * If there was an error obtaining the WNS Channel URI, make sure you've replaced the zero'ed out remote id (near the top of the sample) with your own remote id.