Add note on Jinja2 rendering

Author: dannyadair

README.md

@@ -108,6 +108,9 @@ and gives you full control - for example, one document may create just one PDF f
 another might creates half a dozen variations of itself. All that logic is in your
 `bake.py`.
 
+Start by designing a page in your favourite SVG editor, then use Jinja2 notation to replace text with variables, use conditions, loops etc..<br>
+Your entire configuration will be available in the context of each page - the main config file merged with the document config file merged with the page config file.
+
 ## Development
 
 The source code of pdfbaker [lives on github](https://github.com/pythonnz/pdfbaker).