docs: create FAQ.md (#10)

FAQ.md

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+# FAQ
+
+Maintained by @eseidel
+
+If you have questions not answered here, please ask (either by filing an issue
+or asking on [Discord](https://discord.gg/9hKJcWGcaB)).
+
+# What is "code push"?
+
+Code push, also referred to as "over the air updates" (OTA) is a cloud service
+we are building to enable Flutter developers to deploy updates directly to
+devices anywhere they have shipped Flutter.  We've currently shown demos using
+Android, but since it's built with Flutter/Dart (and Rust) it will work anywhere
+Flutter works.
+
+The easiest way to see is to watch the [demo
+video](https://www.youtube.com/watch?v=mmKvs0_Zu14&ab_channel=Shorebird).
+
+Code push is a working title.  We'll probably come up with some name to help
+differentiate it.  "Code Push" is a reference to the name of a deploy feature
+used by the React Native community from [Microsoft](appcenter.ms) and
+[Expo](appcenter.ms), neither of which support Flutter.
+
+# What is the status of code push?
+
+As of March 4th, 2023 we've built [a
+demo](https://www.youtube.com/watch?v=mmKvs0_Zu14&ab_channel=Shorebird) and have
+the prototype working on multiple machines and Android phones.
+
+
+# What is the roadmap?
+
+First we're trying to get something working into user's hands.  Our current
+prototype is not ready to support multiple users, but we're working to address
+that.
+
+Eric intends to send out a survey to the mailing list -- sign-up at
+[shorebird.dev](https://shorebird.dev) -- and
+[Discord](https://discord.gg/9hKJcWGcaB) the week of March 6th, 2023 from which
+we will find users to work with us on a first version.
+
+# How does this relate to Firebase Remote Config or Launch Darkly?
+
+Code push allows adding new code / replacing code on the device.  Firebase
+Remote Config and Launch Darkly are both configuration systems.  They allow you
+to change the configuration of your app without having to ship a new version.
+They are not intended to replace code.
+
+# How big of a dependency footprint does this add?
+
+We don't know yet.  We expect the code push library to add less than one
+megabyte to Flutter apps.
+
+
+# How does this relate to Flutter Hot Reload?
+
+Flutter's Hot reload is a development-time-only feature.  Code push is for
+production.
+
+Hot reload is a feature of Flutter that allows you to change code on the device
+during development.  It requires building the Flutter engine with a debug-mode
+Dart VM which includes a just-in-time (JIT) Dart compiler.
+
+Code push is a feature that allows you to change code on the device in
+production.  We will use a variety of different techniques to make this possible
+depending on the platform.  Current demos execute ahead-of-time compiled Dart
+code and do not require a JIT Dart compiler.
+
+# Does this support Flutter Web?
+
+Code push isn't needed for Flutter web as the web already works this way.  When
+a user opens a web app it downloads the latest version from the server if
+needed.
+
+If you have a use case for code push with Fluter web, we'd love to know!
+
+# Will this work on iOS, Android, Mac, Windows, Linux, etc?
+
+Yes.
+
+So far we've been using Android for our demos, but code push will eventually
+work everywhere Flutter works. We're focusing on building out the infrastructure
+needed to provide code push reliably, safely first before targeting any specific
+platform.
+
+There are different technical restrictions on some platforms (e.g. iOS) relative
+to Android, but we have several approaches we can use to solve them (Dart is an
+incredibly flexible language).
+
+# How does this relate to the App/Play Store review process or policies?
+
+Developers are bound by their agreements with store providers when they choose
+to use those stores.  Code push is designed to allow developers to update their
+apps and still comply with store policies on iOS and Android.  Similar to the
+variety of commercial products available to do so with React Native (e.g.
+[Microsoft](https://appcenter.ms), [Expo](https://expo.dev)).
+
+We will include more instructions and guidelines about how to both use code push
+and comply with store guidelines as we get closer to a public launch.
+
+# Does code push require the internet to work?
+
+Yes.  One could imagine running a server to distribute the updates separately
+from the general internet, but some form of network connectivity is required to
+transport updates to the devices.
+
+
+# What happens if a user doesn't update for a long time and misses an update?
+
+Our current designs for code push send the current app version & code signature
+as part of the update request.  Thus the update server could be written to
+respond with either the next incremental version or the latest version depending
+on your application's needs.  The current demo always sends the latest version
+but this logic would not be hard to add.