DOC: Syntax hightlighting in README

Author: thewtex

README.md

@@ -13,16 +13,16 @@ Installation
 
 To install the ITK Python package:
 
-```
-    $ pip install itk
+```sh
+     pip install itk
 ```
 
 Usage
 -----
 
 ### Simple example script
 
-```
+```python
     import itk
     import sys