Doc: Format STYLE_GUIDE play nice w/ GFM & PyMD

- Try to format some code in such a way that the rendering is OK with GFM and python markdown (FORD)

Author: zbeekman

STYLE_GUIDE.md

@@ -44,21 +44,21 @@ focus on the semantics of the proposed changes rather than style and formatting.
 
 ## Attributes
 
+<!-- ATTENTION! This section includes intentional trailing whitespace to get decent formatting with GFM and Python Markdown. -->
+
 * Always specify `intent` for dummy arguments.
 * Don't use `dimension` attribute to declare arrays because it is less verbose.
-  Use this:
-
+  Use this:  
   ```
   real, allocatable :: a(:), b(:,:)
-  ```
-
-  instead of:
-
+  ```  
+  instead of:  
   ```
   real, dimension(:), allocatable :: a
-  real, dimension(:,:), allocatable :: b
+  ```  
   ```
-
+  real, dimension(:,:), allocatable :: b
+  ```  
   When defining many arrays of the same dimension, `dimension` can be used as an exception if it makes the code less verbose.
 * If the `optional` attribute is used to declare a dummy argument, it should follow the `intent` attribute.