add sample

README.md

@@ -13,6 +13,55 @@ Using composer from [packagist](https://packagist.org/packages/greenter/htmltopd
 composer require greenter/htmltopdf
 ```
 
+## Example
+Require [html-report](https://github.com/giansalex/greenter-report) and logo.png
+
+```php
+use Greenter\Report\HtmlReport;
+use Greenter\Report\PdfReport;
+use Greenter\Model\Sale\Invoice;
+
+$invoice = new Invoice();
+// fill ...
+
+$html = new HtmlReport('', [
+    'cache' => __DIR__ . '/cache',
+    'strict_variables' => true,
+]);
+$html->setTemplate('invoice.html.twig');
+
+$report = new PdfReport($html);
+$report->setOptions( [
+    'no-outline',
+    'viewport-size' => '1280x1024',
+    'page-width' => '21cm',
+    'page-height' => '29.7cm',
+]);
+$report->setBinPath('wkhtmltopdf.exe');
+
+$logo = file_get_contents(__DIR__.'/logo.png');
+$params = [
+    'system' => [
+        'logo' => $logo,
+        'hash' => ''
+    ],
+    'user' => [
+        'resolucion' => '212321',
+        'header'     => 'Telf: <b>(056) 123375</b>',
+        'extras'     => [
+            ['name' => 'CONDICION DE PAGO', 'value' => 'Efectivo'     ],
+            ['name' => 'VENDEDOR'         , 'value' => 'GITHUB SELLER'],
+        ],
+    ]
+];
+
+$pdf = $report->render($invoice, $params);
+
+// Write PDF to disk
+file_put_contents('invoice.pdf', $pdf);
+
+```
+
 ## Preview
 Representacion Impresa de la Factura Electrónica.