Add function-scoped static variable example to New in initializers docs

[imaarov]

I think demonstrating a static variable that holds an object in a function is essential to include in this document, for example :

<?php

class Foo {
	public string $name;
	public function __construct(string $name) {
		$this->name = $name;
	}
}

function testStatic(?string $entryName = NULL) {
    static $x = new Foo($entryName);
	echo $x->name, PHP_EOL;
    
}
testStatic('iman'); // output : iman
testStatic();       // output : iman (as the object type is static in function, it retains its state)