Fixed typo in Zach's surname

Author: markwalkom

Preface.asciidoc

@@ -250,7 +250,7 @@ Do not edit this section.
 
 This book is here to help you get your job done. In general, if example code is offered with this book, you may use it in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.
 
-We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: _Elasticsearch: The Definitive Guide_ by Clinton Gormley and Zachary Tony (O’Reilly). Copyright 2015 Elasticsearch BV, 978-1-449-35854-9.
+We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: _Elasticsearch: The Definitive Guide_ by Clinton Gormley and Zachary Tong (O’Reilly). Copyright 2015 Elasticsearch BV, 978-1-449-35854-9.
 
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 If you feel your use of code examples falls outside fair use or the permission given above, feel free to contact us at