Add more information about PdfPreview

@@ -134,6 +134,28 @@ final pdf = await rootBundle.load('document.pdf');
 await Printing.layoutPdf(onLayout: (_) => pdf.buffer.asUint8List());
 await Printing.layoutPdf(onLayout: (_) => pdf.buffer.asUint8List());
 ```
 ```
 
 
+## Display your PDF document
+
+This package also comes with a PdfPreview widget to display a pdf document.
+
+```dart
+PdfPreview(
+  build: (format) => doc.save(),
+);
+```
+
+This widget is compatible with Android, iOS, macOS and web.
+
+For the web, a javascript library and a small script has to be added to
+your `web/index.html` file:
+
+```html
+<script src="//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.4.456/pdf.min.js"></script>
+<script type="text/javascript">
+     pdfjsLib.GlobalWorkerOptions.workerSrc = "//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.4.456/pdf.worker.min.js";
+</script>
+```
+
 ## Designing your PDF document
 ## Designing your PDF document
 
 
 A good starting point is to use PdfPreview which features hot-reload pdf build
 A good starting point is to use PdfPreview which features hot-reload pdf build
@@ -161,7 +183,7 @@ Future<Uint8List> _generatePdf(PdfPageFormat format, String title) async {
 This widget also features a debug switch at the bottom right to display the
 This widget also features a debug switch at the bottom right to display the
 drawing constraints used. This switch is available only on debug builds.
 drawing constraints used. This switch is available only on debug builds.
 
 
-Moving on to your production application, you can keep only the `_generatePdf`
+Moving on to your production application, you can keep the `_generatePdf`
 function and print the document using:
 function and print the document using:
 
 
 ```dart
 ```dart