Fix #553: Add example for sending a POST request with XML data

examples/post_xml.php

@@ -0,0 +1,29 @@
+<?php
+require __DIR__ . '/../vendor/autoload.php';
+
+use \Curl\Curl;
+
+$data = '<?xml version="1.0" encoding="UTF-8"?>
+<rss>
+    <items>
+        <item>
+            <id>1</id>
+            <ref>33ee7e1eb504b6619c1b445ca1442c21</ref>
+            <title><![CDATA[The Title]]></title>
+            <description><![CDATA[The description.]]></description>
+            <link><![CDATA[https://www.example.com/page.html?foo=bar&baz=wibble#hash]]></link>
+        </item>
+        <item>
+            <id>2</id>
+            <ref>b5c0b187fe309af0f4d35982fd961d7e</ref>
+            <title><![CDATA[Another Title]]></title>
+            <description><![CDATA[Some description.]]></description>
+            <link><![CDATA[https://www.example.org/image.png?w=1265.73&h=782.26]]></link>
+        </item>
+    </items>
+</rss>';
+
+$curl = new Curl();
+$curl->setHeader('Content-Type', 'text/xml');
+$curl->post('https://httpbin.org/post', $data);
+var_dump($curl->response);