Add File IO instrumentation docs

src/platform-includes/getting-started-primer/dart.mdx

@@ -15,5 +15,6 @@ Sentry's Dart SDK enables automatic reporting of errors, messages, and exception
 - [Performance Monitoring](/product/performance/) creates transactions for:
     - [HTTP requests](/platforms/dart/configuration/integrations/http-integration/#performance-monitoring-for-http-requests)
     - [Dio HTTP library](/platforms/dart/configuration/integrations/dio/#performance-monitoring-for-http-requests)
+    - [File I/O Integration](/platforms/dart/configuration/integrations/file/)
 - [Logging Integration](/platforms/dart/configuration/integrations/logging)
 - [Dio Integration](/platforms/dart/configuration/integrations/dio/)

src/platform-includes/getting-started-primer/flutter.mdx

@@ -30,6 +30,7 @@ Features:
   - [Cold and warm app start](/platforms/flutter/performance/instrumentation/automatic-instrumentation/#app-start-instrumentation)
   - [Slow and frozen frames](/platforms/flutter/performance/instrumentation/automatic-instrumentation/#slow-and-frozen-frames)
   - [AssetBundle Instrumentation](/platforms/flutter/performance/instrumentation/automatic-instrumentation/#assetbundle-instrumentation)
+  - [File I/O Integration](/platforms/dart/configuration/integrations/file/)
 - [Logging Integration](/platforms/dart/configuration/integrations/logging)
 - [Screenshot attachments for errors](/platforms/flutter/enriching-events/screenshots/)
 - Limited support for Flutter Web, Windows, and Linux

src/platforms/dart/common/performance/instrumentation/automatic-instrumentation.mdx

@@ -31,3 +31,15 @@ The span finishes once the request has been executed. The span `status` depends
 When the HTTP request throws an `Exception`, Sentry's SDK associates this exception to the running span. If you haven't set the SDK to swallow the exception and capture it, the span and `SentryEvent` will be linked when viewing it on the **Issue Details** page in [sentry.io](https://sentry.io).
 
 Learn more in our [Dio integration documentation](/platforms/dart/configuration/integrations/dio/#performance-monitoring-for-http-requests).
+
+### File I/O Instrumentation
+
+The Sentry-specific file I/O implementation starts a span out of the active span, bound to the scope for each file I/O operation. The SDK sets the span `operation` to `file.copy`/`file.write`/`file.delete`/`file.open`/`file.read`/`file.rename` and `description` to `filename`, e.g. `file.txt`
+
+In addition, the span contains other useful information such as `file.size` (raw number of bytes), `file.path` (an absolute path to the file) and `file.async` (`true` if the called method returns a `Future` or `false` if it's a `Sync` call) as part of the `data` payload.
+
+The span finishes once the operation has been executed. The span `status` is set to `SpanStatus.ok` if successful or `SpanStatus.internalError` if there was any error.
+
+When the operation throws an `Exception`, Sentry's SDK associates this exception to the running span. If you haven't set the SDK to swallow the exception and capture it, the span and SentryEvent will be linked when viewing it on the **Issue Details** page in sentry.io.
+
+For more information see our [file I/O integration](/platforms/dart/configuration/integrations/file/).

src/platforms/dart/configuration/integrations/file.mdx

@@ -0,0 +1,90 @@
+---
+title: File I/O
+sidebar_order: 5
+description: "Learn more about the Sentry file I/O integration for the Dart SDK."
+---
+
+<Note>
+
+This feature is currently in Beta. Beta features are still in-progress and may have bugs. We recognize the irony.
+
+</Note>
+
+The `sentry_file` library provides [File](https://api.dart.dev/stable/2.18.5/dart-io/File-class.html) support for Sentry wrapping the `File` class with a `SentryFile` wrapper. It is able to run performance monitoring for `File` operations.
+
+The source can be found [on GitHub](https://github.com/getsentry/sentry-dart/tree/main/file/).
+
+On this page, we get you up and running with Sentry's file I/O integration, so that it will automatically start a span out of the active transaction, bound to the scope for operations such as `copy`, `create`, `delete`, `open`, `rename`, `read` and `write`.
+
+<Note>
+
+The File I/O integration is only available for the `dart:io:File` class, not for the `dart:html:File` class.
+
+</Note>
+
+## Install
+
+To use the `SentryFile` wrapper, add the `sentry_file` dependency.
+
+```yml {filename:pubspec.yaml}
+dependencies:
+  sentry: ^{{ packages.version('sentry.dart', '6.18.0') }}
+  sentry_file: ^{{ packages.version('sentry.dart.file', '6.18.0') }}
+```
+
+## Verify
+
+<Note>
+
+Capturing transactions requires that you first <PlatformLink to="/performance/">set up performance monitoring</PlatformLink> if you haven't already.
+
+</Note>
+
+```dart
+import 'package:sentry/sentry.dart';
+import 'package:sentry_file/sentry_file.dart';
+import 'dart:io';
+
+Future<void> main() async {
+  await Sentry.init(
+    (options) {
+      options.dsn = 'https://[email protected]/example';
+      // To set a uniform sample rate
+      options.tracesSampleRate = 1.0;
+    },
+    appRunner: runApp, // Init your App.
+  );
+}
+
+Future<void> runApp() async {
+  final file = File('my_file.txt');
+  // Call the Sentry extension method to wrap up the File
+  final sentryFile = file.sentryTrace();
+
+  // Start a transaction if there's no active transaction
+  final transaction = Sentry.startTransaction(
+    'MyFileExample',
+    'file',
+    bindToScope: true,
+  );
+
+  // create the File
+  await sentryFile.create();
+  // Write some content
+  await sentryFile.writeAsString('Hello World');
+  // Read the content
+  final text = await sentryFile.readAsString();
+
+  print(text);
+
+  // Delete the file
+  await sentryFile.delete();
+
+  // Finish the transaction
+  await transaction.finish(status: SpanStatus.ok());
+
+  await Sentry.close();
+}
+```
+
+To view the recorded transaction, log into [sentry.io](https://sentry.io) and open your project. Clicking  **Performance** will open a page with transactions, where you can select the just recorded transaction with the name `MyFileExample`.

src/platforms/flutter/common/performance/instrumentation/automatic-instrumentation.mdx

@@ -213,3 +213,15 @@ The `SentryAssetBundle` instrumentation starts a span out of the active transact
 The `enableStructuredDataTracing` feature is available in Beta. Beta features are still in-progress and may have bugs. We recognize the irony.
 
 </Note>
+
+### File I/O Instrumentation
+
+The Sentry-specific file I/O implementation starts a span out of the active span, bound to the scope for each file I/O operation. The SDK sets the span `operation` to `file.copy`/`file.write`/`file.delete`/`file.open`/`file.read`/`file.rename` and `description` to `filename`, e.g. `file.txt`
+
+In addition, the span contains other useful information such as `file.size` (raw number of bytes), `file.path` (an absolute path to the file) and `file.async` (`true` if the called method returns a `Future` or `false` if it's a `Sync` call) as part of the `data` payload.
+
+The span finishes once the operation has been executed. The span `status` is set to `SpanStatus.ok` if successful or `SpanStatus.internalError` if there was any error.
+
+When the operation throws an `Exception`, Sentry's SDK associates this exception to the running span. If you haven't set the SDK to swallow the exception and capture it, the span and SentryEvent will be linked when viewing it on the **Issue Details** page in sentry.io.
+
+For more information see our [file I/O integration](/platforms/dart/configuration/integrations/file/).