Change url for Mastering Object-Orientated PHP book [skip ci]

README.md

@@ -911,7 +911,7 @@ Various resources, such as books, websites and articles, for improving your PHP
 * [Domain-Driven Design in PHP](https://leanpub.com/ddd-in-php) - Real examples written in PHP showcasing DDD Architectural Styles.
 * [Functional Programming in PHP](https://www.functionalphp.com/) - This book will show you how to leverage these new PHP5.3+ features by understanding functional programming principles
 * [Grumpy PHPUnit](https://leanpub.com/grumpy-phpunit) - A book about unit testing with PHPUnit by Chris Hartjes.
-* [Mastering Object-Orientated PHP](https://brandonsavage.net) - A book about object-orientated PHP by Brandon Savage.
+* [Mastering Object-Orientated PHP](https://masteringobjectorientedphp.com/) - A book about object-orientated PHP by Brandon Savage.
 * [Modern PHP New Features and Good Practices](https://www.oreilly.com/library/view/~/9781491905173/) - A book about new PHP features and best practices by Josh Lockhart.
 * [Modernizing Legacy Applications in PHP](https://leanpub.com/mlaphp) - A book about modernizing legacy PHP applications by Paul M. Jones.
 * [PHP 7 Upgrade Guide](https://leanpub.com/php7) - An ebook covering all of the features and changes in PHP 7 by Colin O'Dell.