Add PR template and update readme (#59)

.github/PULL_REQUEST_TEMPLATE

@@ -0,0 +1,5 @@
+<!--
+Important note: This repo exists to provide a basic demonstration of how the expo-updates protocol can be translated to code. It is not designed to be complete, stable, or performant enough to use as a full-fledged backend for expo-updates. Any pull requests that add new features will likely be closed; instead, feel free to fork the repository to add new features.
+
+If submitting a pull request for a bug fix, please describe the bug and how this PR fixes it.
+-->

README.md

@@ -3,7 +3,7 @@
 This repo contains a server and client that implement the [Expo Updates protocol specification](https://docs.expo.dev/technical-specs/expo-updates-0).
 
 > [!IMPORTANT]
-> This repo exists to provide a basic demonstration of how the protocol might be translated to code. It is not guaranteed to be complete, stable, or performant enough to use as a backend for expo-updates. Expo does not provide hands-on technical support for custom expo-updates server implementations, including what is in this repo. Issues within the expo-updates client library itself (independent of server) may be reported at https://github.com/expo/expo/issues/new/choose.
+> This repo exists to provide a basic demonstration of how the protocol might be translated to code. It is not guaranteed to be complete, stable, or performant enough to use as a full-fledged backend for expo-updates. Expo does not provide hands-on technical support for custom expo-updates server implementations, including what is in this repo. Issues within the expo-updates client library itself (independent of server) may be reported at https://github.com/expo/expo/issues/new/choose. Any pull requests that add new features to this repository will likely be closed; instead, feel free to fork the repository to add new features.
 
 ## Why