Markdown syntax to show code changes

The below markup shows how to display code change on Github using markdown.

    ``` diff
    - delete this code
    + add this code
    ```

the above code would output

- delete this code
+ add this code

Make sure the plus and minus lines link up with the back thicks or the red and green highlighting will not work. for example I have the following NOTE the + and - to not line up with the backticks, it is slight but there is a space before the code lines.

    ``` diff
     - delete this code
     + add this code
    ```

and the bad output will be displayed below

     - delete this code
     + add this code