add an other file example to README (#410)

* added file example to README

* Update README.md

Author: fischerscode

README.md

@@ -825,7 +825,7 @@ Have a look at the example application for a small (non web) example.
 
 
 ```dart
-//A short example
+//A short example for showing an image from a ParseFileBase
 Widget buildImage(ParseFileBase image){
   return FutureBuilder<ParseFileBase>(
     future: image.download(),
@@ -844,6 +844,23 @@ Widget buildImage(ParseFileBase image){
   );
 }
 ```
+```dart
+//A short example for storing a selected picture
+//libraries: image_picker (https://pub.dev/packages/image_picker), image_picker_for_web (https://pub.dev/packages/image_picker_for_web)
+PickedFile pickedFile = await ImagePicker().getImage(source: ImageSource.gallery);
+ParseFileBase parseFile;
+if (kIsWeb) {
+  //Seems weird, but this lets you get the data from the selected file as an Uint8List very easily. 
+  ParseWebFile file = ParseWebFile(null, name: null, url: pickedFile.path);
+  await file.download();
+  parseFile = ParseWebFile(file.file, name: file.name);
+} else {
+  parseFile = ParseFile(File(pickedFile.path));
+}
+someParseObject.set("image", parseFile);
+//This saves the ParseObject as well as all of its children, and the ParseFileBase is such a child. 
+await someParseObject.save();
+```
 
 ## Other Features of this library
 Main: