Added README.md

Author: mvanbeusekom

packages/cross_file/README.md

@@ -0,0 +1,34 @@
+# cross_file
+
+An abstraction to allow working with files across multiple platforms.
+
+# Usage
+
+Import `package:cross/cross_info.dart`, instantiate a `CrossFile` 
+using a path or byte array and use its methods and properties to 
+access the file and its metadata.
+
+Example:
+
+```dart
+import 'package:cross_file/cross_file.dart';
+
+final file = CrossFile('assets/hello.txt');
+
+print('File information:');
+print('- Path: ${file.path}');
+print('- Name: ${file.name}');
+print('- MIME type: ${file.mimeType}');
+
+final fileContent = await file.readAsString();
+print('Content of the file: ${fileContent}');  // e.g. "Moto G (4)"
+```
+
+You will find links to the API docs on the [pub page](https://pub.dartlang.org/packages/cross_file).
+
+## Getting Started
+
+For help getting started with Flutter, view our online
+[documentation](http://flutter.io/).
+
+For help on editing plugin code, view the [documentation](https://flutter.io/platform-plugins/#edit-code).