Add screenies for viewing pull requests

Author: jcansdale

docs/contributing/images/pull-request-list.png

@@ -4,8 +4,10 @@ GitHub for Visual Studio exposes the pull requests for the current repository an
 
 1. [Sign in](authenticating-to-github) to GitHub.
 2. Open a solution in a GitHub repository.
-3. Open **Team Explorer** and click the **Pull Requests** button to open the **GitHub** pane. TODO: screenshot
-4. The open pull requests will be displayed. TODO: screenshot
+3. Open **Team Explorer** and click the **Pull Requests** button to open the **GitHub** pane.
+![Pull Requests](images/pull-requests-button2.png)
+4. The open pull requests will be displayed.
+![Open Pull Requests](images/pull-request-list.png)
 5. Change the Open/Closed filter by clicking the **Open** link and selecting the filter you want to use from the dropdown.
 6. Filter pull requests by Assignee by clicking the **Assignee** link and selecting the assignee you want to view from the dropdown.
 7. Filter pull requests by Author by clicking the **Author** link and selecting the author you want to view from the dropdown.