Fix titles in README.md

Author: FrederikBjorne

README.md

@@ -50,12 +50,12 @@ NewValuePublisher updating new value: 6 to observers
 NewValueSubscriber1 received new value: 6
 ```
 
-##Prerequisites
+## Prerequisites
 
 Works for both Python2.6+ or python3
 [Install python](https://www.python.org/downloads/)
 
-##Install this package directly
+## Install this package directly
 Get observer package by issuing the following command:
 ```console
 $ pip install git+https://github.com/FrederikBjorne/python-observer.git