chore(README): add installation instructions

README.md

@@ -48,3 +48,36 @@ These are the official Revenge ways to install Revenge:
 
 - **📵 Non-root**: [Revenge Manager](https://github.com/revenge-mod/revenge-manager/releases/latest)
 - **🩹 Root with Xposed**: [RevengeXposed](https://github.com/revenge-mod/revenge-xposed/releases/latest)
+
+Using the installation methods above will currently install [Revenge Classic](https://github.com/revenge-mod/revenge-bundle). You'll need to update from Revenge Classic to Revenge Next manually.
+
+### ⬆️ Updating to Revenge Next
+
+> **It is recommended to do a separate installation of Revenge before updating to Revenge Next.**  
+> Revenge Next does not offer an easy way to downgrade to Revenge Classic.
+
+To update to Revenge Next from Revenge Classic, follow these steps:
+
+1. Download the latest release asset from [Revenge Next's Actions tab](https://github.com/revenge-mod/revenge-bundle-next/actions/workflows/build.yml).
+2. Extract the built bundle and host a local HTTP server that serves the `revenge.bundle` file.
+3. In Revenge Classic, go to **Settings** > **Revenge**, and toggle on **Developer Settings**.
+4. Navigate back, and head into the **Developer** section.
+5. Edit the **Load from custom URL** field to point to the URL of the `revenge.bundle` file you hosted.
+6. Restart Discord, and you should be running Revenge Next!
+
+### 🔄️ Updating builds
+
+Revenge Next is updated regularly with new features and bug fixes. To update to the latest build, follow these steps:
+
+1. Host a HTTP server that points to a new `revenge.bundle` file.
+2. Head to **Settings** > **Revenge** > **Developer**.
+3. Tap on the **Evaluate JavaScript** option.
+4. Paste and evaluate the following snippet. Make sure to modify the URL to point to your newly hosted `revenge.bundle` file:
+
+    ```js
+    var REVENGE_UPDATE_URL = "<URL here, keep the quotes>";
+    revenge.discord.native.FileModule.writeFile("documents", "pyoncord/loader.json", JSON.stringify({"customLoadUrl":{"enabled":true,"url":REVENGE_UPDATE_URL}}), "utf8");
+    "URL updated, please reload Revenge"
+    ```
+
+5. Restart Discord.