Update Doctrine Extensions link

The project moved from https://github.com/l3pp4rd/DoctrineExtensions to https://github.com/Atlantic18/DoctrineExtensions

README.md

 *Libraries for interacting with databases using object-relational mapping (ORM) or datamapping techniques.*
 
 * [Doctrine](http://www.doctrine-project.org/) - A comprehensive DBAL and ORM.
-* [Doctrine Extensions](https://github.com/l3pp4rd/DoctrineExtensions) - A collection of Doctrine behavioural extensions.
+* [Doctrine Extensions](https://github.com/Atlantic18/DoctrineExtensions) - A collection of Doctrine behavioural extensions.
 * [Propel](http://propelorm.org/) - A fast ORM, migration library and query builder.
 * [Eloquent](https://github.com/illuminate/database) - A simple ORM (L5).
 * [LazyRecord](https://github.com/c9s/LazyRecord) - A fast ORM designed for simplicity, extendability and performance.