Updating code block.

README.md

@@ -9,9 +9,9 @@ It's have been successfully tested in GNU/Linux, Microsoft Windows 7 and Mac OS
 The openComtradeViewer is developed with Python language, version 2.7. Therefore, to properly run it will be necessary to have the Python interpreter installed on your computer. Nevertheless, some non-standard libraries will be needed as well. If you run GNU/Linux, Mac OS X or other unix-flavor operating system you probably have Python interpreter installed. However, if you use Microsoft Windows there is a great chance that you will need to [install the interpreter by yourself](https://www.python.org/downloads/).
 
 The installation of openComtradeViewer and its dependecies is simple in all OSs and can be performed with the simple command line below:
-'''
+```
 pip install https://github.com/ldemattos/openComtradeViewer/archive/master.zip --user --upgrade
-'''
+```
 
 ## Usage Guidance