Add gitception image.

Author: ian-r-rose

README.md

@@ -11,6 +11,9 @@ repositories. If those files are notebooks, you can run them just as you would
 any other notebook. You can also attach a kernel to text files and run those.
 Basically, you should be able to open any file in a repository that JupyterLab can handle.
 
+Here is a screenshot of the plugin opening this very file on GitHub:
+![gitception](gitception.png "Gitception")
+
 ### What this extension is not
 
 This is not an extension that provides full GitHub access, such as
@@ -87,4 +90,4 @@ c.GitHubConfig.client_secret = '< YOUR_CLIENT_SECRET >'
 ```
 where "`< YOUR_CLIENT_ID >`" and "`< YOUR_CLIENT_SECRET >`" are the string values you obtained above.
 
-With this, you should be done! Launch JupyterLab and look for the GitHub tab on the left!
+With this, you should be done! Launch JupyterLab and look for the GitHub tab on the left!