README.md updated

Author: s3b4stian

README.md

@@ -7,5 +7,27 @@
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-## About this package
-Typed arrays for php
+## Typed arrays for php
+Provide typed arrays for php as extension of native [ArrayObject](http://php.net/manual/en/class.arrayobject.php)
+
+## Requirements
+This package require php 7.
+
+## Installation
+With composer:
+```
+composer require s3b4stian/linna-array
+```
+
+## Usage
+```php
+use Linna\intArray;
+
+//correct, only int passed to array.
+$array = new intArray([1,2,3,4]);
+$array[] = 5;
+
+//throw TypeError.
+$array = new intArray([1,'a',3,4]);
+$array[] = 'a';
+```