Fixed examples, and made some self-contained を取り込み

差分ページ
php/doc-en@d6f5401#diff-efd8446f27c7eac04b8ed976baac78ce391a5486b44bd167287bad4fe8a5c0d3

Author: siwa32

language/oop5/property-hooks.xml

@@ -213,6 +213,7 @@ class Example
    </simpara>
    <programlisting role="php">
 <![CDATA[
+<?php
 class Example
 {
     public function __construct(
@@ -234,6 +235,7 @@ class Example
    </simpara>
    <programlisting role="php">
 <![CDATA[
+<?php
 class Example
 {
     public private(set) DateTimeInterface $created {