upload_to_testflight.md in fastlane-2.157.0

- old
+ new

@@ -24,10 +24,26 @@
 
 <h5 align="center"><em>pilot</em> is part of <a href="https://fastlane.tools">fastlane</a>: The easiest way to automate beta deployments and releases for your iOS and Android apps.</h5>
 
 # Usage
 
-For all commands you can specify the Apple ID to use using `-u felix@krausefx.com`. If you execute _pilot_ in a project already using [_fastlane_](https://fastlane.tools) the username and app identifier will automatically be determined.
+For all commands, you can either use an [API Key](#app-store-connect-api-key) or your [Apple ID](#apple-id).
+
+### App Store Connect API Key
+
+The App Store Connect API Key is the preferred authentication method (if you are able to use it).
+
+- Uses offial App Store Connect API
+- No need for 2FA
+- Better performance over Apple ID
+
+Specify the API key using `--api_key_path ./path/to/api_key_info.json` or `--api_key "{\"key_id\": \"D83848D23\", \"issuer_id\": \"227b0bbf-ada8-458c-9d62-3d8022b7d07f\", \"key_filepath\": \"D83848D23.p8\"}"`
+
+Go to [Using App Store Connect API](/app-store-connect-api) for information on obtaining an API key, the _fastlane_ `api_key_info.json` format, and other API key usage.
+
+### Apple ID
+
+Specify the Apple ID to use using `-u felix@krausefx.com`. If you execute _pilot_ in a project already using [_fastlane_](https://fastlane.tools) the username and app identifier will automatically be determined.
 
 ## Uploading builds
 
 To upload a new build, just run
 