Updated README.

Author: vscheuber

README.md

@@ -22,8 +22,9 @@ A sample tree could look like this:
 Note: The user is first properly authenticated using username and password, only then does she reach the PPC node.
 
 A few sample dialogs:
-
-<img src="./example_dialog_footer.png" alt="Footer with links" width="250"/><img src="./example_dialog_message.png" alt="Message with custom button text" width="250"/><img src="./example_dialog_variable.png" alt="Personalized greeting" width="250"/>
+Footer with links | Message with custom button text | Personalized greeting
+----------------- | ------------------------------- | ---------------------
+<img src="./example_dialog_footer.png" alt="Footer with links" width="250"/> | <img src="./example_dialog_message.png" alt="Message with custom button text" width="250"/> | <img src="./example_dialog_variable.png" alt="Personalized greeting" width="250"/>
 
 ## Settings
 Setting             | Description