Add screenies for creating a PR

Author: jcansdale

docs/contributing/creating-a-pull-request.md

@@ -1,8 +1,10 @@
 # Creating a pull request
 
 1. Open a solution in a GitHub repository.
-2. Open **Team Explorer** and click the **Pull Requests** button to open the **GitHub** pane. TODO: screenshot
+2. Open **Team Explorer** and click the **Pull Requests** button to open the **GitHub** pane.
+![Pull Requests](images/pull-requests-button2.png)
 3. Click the **Create New** link above the list of pull requests for the repository.
-4. Select the target branch by clicking the link. If the current repository is a fork, then there will be two sets of branches in the dropdown - to submit a pull request upstream then select a branch with the `owner:` prefix of the upstream repository. TODO: screenshot
+4. Select the target branch by clicking the link. If the current repository is a fork, then there will be two sets of branches in the dropdown - to submit a pull request upstream then select a branch with the `owner:` prefix of the upstream repository.
+![](images/pr-create.png)
 5. Enter a pull request title and an optional description.
 6. Click the **Create Pull Request** button.