fix(shorebird_cli): update ios upload instructions to match Flutter

[bryanoltman]

Description

Updates the post-release instructions for shorebird release ios to more closely match those of flutter build ipa.

Flutter:

To upload to the App Store either:
    1. Drag and drop the "build/ios/ipa/*.ipa" bundle into the Apple Transporter macOS app
    https://apps.apple.com/us/app/transporter/id1450874784
    2. Run "xcrun altool --upload-app --type ios -f build/ios/ipa/*.ipa --apiKey your_api_key --apiIssuer your_issuer_id".
       See "man altool" for details about how to authenticate with the App Store Connect API key.

Shorebird, with this PR:

Your next step is to upload your app to App Store Connect.

To upload to the App Store, do one of the following:
    1. Open build/ios/archive/Runner.xcarchive in Xcode and use the "Distribute App" flow.
    2. Drag and drop the build/ios/ipa/*.ipa bundle into the Apple Transporter macOS app (https://apps.apple.com/us/app/transporter/id1450874784).
    3. Run xcrun altool --upload-app --type ios -f build/ios/ipa/*.ipa --apiKey your_api_key --apiIssuer your_issuer_id.
       See "man altool" for details about how to authenticate with the App Store Connect API key.

Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 🛠️ Bug fix (non-breaking change which fixes an issue)
• ❌ Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Code refactor
• ✅ Build configuration change
• 📝 Documentation
• 🗑️ Chore
• 🧪 Tests

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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