Fix markdown linter errors

Author: michel-kraemer

README.md

@@ -391,6 +391,7 @@ next to it. This icon means the component is part of the official
 * [Blog](http://vertx.io/blog/) - The official Vert.x blog containing many tutorials and other information.
 
 ## Articles
+
 * [Embracing Reactive Applications on JVM: a Deep Dive into Modern I/O Models and Vert.x](https://www.infoq.com/articles/reactive-java-vertx-deep-dive/)
 * [Going reactive with Eclipse Vert.x and RX Java](https://blogs.oracle.com/javamagazine/post/going-reactive-with-eclipse-vertx-and-rxjava)
 * [Vert.x 3.3.0 Features Enhanced Networking Microservices, Testing and More](https://www.infoq.com/news/2016/06/Vert.x-3.3.0-release-features)