Diff syntax highlighting in Github Markdown

Solution 1:

Github's markdown supports diff when formatting code. For example:

```diff
public class Hello1
{
   public static void Main()
   {
-      System.Console.WriteLine("Hello, World!");
+      System.Console.WriteLine("Rock all night long!");
   }
}
```

Output:

and it should give you the Diff looks you are looking for, highlighting in red what has been removed and in green what has been added.

Solution 2:

Salvador's response is correct, however, I found out that you should add the diff header to the code snippet in order to highlight it:

``` diff
diff --git a/filea.extension b/fileb.extension
index d28nd309d..b3nu834uj 111111
--- a/filea.extension
+++ b/fileb.extension
@@ -1,6 +1,6 @@
-oldLine
+newLine
```

I hope that helps!