Add missing carriage return

7. was not shown correctly in the docs.

docs/extending.rst

@@ -85,6 +85,7 @@ To do the setup you need to perform the steps from the following chapters in a c
             docker run -d -p 6379:6379 --restart unless-stopped redis:latest
 
 7.  Install the python dependencies by performing in the src/ directory.
+
     .. code:: shell-session
 
         pipenv install --dev