README: fix markdown formatting

The old format doesn't render correctly in GitHub.

README.md

@@ -32,9 +32,11 @@ not practical to start over at 1.0.
 1. Install base dependencies:
 
     ***
+
     Requirements:
     - Ansible >= 2.1.0 (>= 2.2 is preferred for performance reasons)
     - Jinja >= 2.7
+
     ***
 
     Fedora: