Remove Collections

In my opinion, it makes sense to remove this recommendation from the list as this package is archived by the owner and is not maintained anymore.

README.md

 *Libraries that implement data structure or storage techniques.*
 
 * [Cake Collection](https://github.com/cakephp/collection) - A simple collections library (CP).
-* [Collections](https://github.com/italolelis/collections) - Collections Abstraction library for PHP.
 * [Fractal](https://github.com/thephpleague/fractal) - A library for converting complex data structures to JSON output.
 * [Ginq](https://github.com/akanehara/ginq) - Another PHP library based on .NET's LINQ.
 * [JsonMapper](https://github.com/cweiske/jsonmapper) - A library that maps nested JSON structures onto PHP classes.