Update the io_file description to be (semi) useful. (#238)

Author: brianquinlan

README.md

@@ -10,7 +10,7 @@ This repository is home to various Dart packages under the
 | [appengine](pkgs/appengine/) | Support for using Dart as a custom runtime on Google App Engine Flexible Environment. | [![package issues](https://img.shields.io/badge/issues-4774bc)](https://github.com/dart-lang/labs/issues?q=is%3Aissue%20state%3Aopen%20label%3Apackage%3Aappengine) | [![pub package](https://img.shields.io/pub/v/appengine.svg)](https://pub.dev/packages/appengine) |
 | [gcloud](pkgs/gcloud/) | High level idiomatic Dart API for Google Cloud Storage, Pub-Sub and Datastore. | [![package issues](https://img.shields.io/badge/issues-4774bc)](https://github.com/dart-lang/labs/issues?q=is%3Aissue%20state%3Aopen%20label%3Apackage%3Agcloud) | [![pub package](https://img.shields.io/pub/v/gcloud.svg)](https://pub.dev/packages/gcloud) |
 | [googleapis_firestore_v1](pkgs/googleapis_firestore_v1/) | An experimental gRPC client for the Cloud Firestore API. | [![package issues](https://img.shields.io/badge/issues-4774bc)](https://github.com/dart-lang/labs/issues?q=is%3Aissue%20state%3Aopen%20label%3Apackage%3Agoogleapis_firestore_v1) |
-| [io_file](pkgs/io_file/) | TBD | [![package issues](https://img.shields.io/badge/issues-4774bc)](https://github.com/dart-lang/labs/issues?q=is%3Aissue%20state%3Aopen%20label%3Apackage%3Aio_file) |
+| [io_file](pkgs/io_file/) | File system access functionality written in Dart. | [![package issues](https://img.shields.io/badge/issues-4774bc)](https://github.com/dart-lang/labs/issues?q=is%3Aissue%20state%3Aopen%20label%3Apackage%3Aio_file) |
 | [native_synchronization](pkgs/native_synchronization/) | Low level synchronization primitives built on dart:ffi. | [![package issues](https://img.shields.io/badge/issues-4774bc)](https://github.com/dart-lang/labs/issues?q=is%3Aissue%20state%3Aopen%20label%3Apackage%3Anative_synchronization) | [![pub package](https://img.shields.io/pub/v/native_synchronization.svg)](https://pub.dev/packages/native_synchronization) |
 
 ## Publishing automation

pkgs/io_file/pubspec.yaml

@@ -1,5 +1,5 @@
 name: io_file
-description: A starting point for Dart libraries or applications.
+description: File system access functionality written in Dart.
 version: 0.1.0-wip
 repository: https://github.com/dart-lang/labs/tree/main/pkgs/io_file
 publish_to: none