Edited Preface.asciidoc with Atlas code editor

Author: skalapurakkel

Preface.asciidoc

@@ -84,7 +84,7 @@ Elasticsearch available at the time of going to print--version 1.4.0--but
 Elasticsearch is a rapidly evolving project.  The online version of this book
 will be updated as Elasticsearch changes.
 
-You can find the latest version of this <a href="http://www.elasticsearch.org/guide/">book online</a>.
+You can find the latest version of this http://www.elasticsearch.org/guide/[book online].
 
 You can also track the changes that have been made by visiting the <a href="https://github.com/elasticsearch/elasticsearch-definitive-guide/">GitHub repository</a>.