docs: move environment setup to monorepo root

docs/0_development_environment.md

@@ -0,0 +1,46 @@
+# 🏗️ Setting up the development environment
+
+> [!IMPORTANT]  
+> **This project uses [Bun](https://bun.sh) to run and bundle the code.**  
+> Compatibility with other runtimes (Node.js, Deno, ...) are not guaranteed and most package scripts won't work.
+
+To start developing, you'll need to set up the development environment first.
+
+1. Install [Bun](https://bun.sh)
+
+2. Clone the mono-repository
+
+    ```sh
+    git clone https://github.com/ReVanced/revanced-helper.git &&
+    cd revanced-helper
+    ```
+
+3. Install dependencies
+
+    ```sh
+    bun install
+    ```
+
+4. Build packages/libraries
+
+    ```sh
+    bun run build
+    ```
+
+5. Change your directory to a project's root
+    ```sh
+    # WebSocket API
+    cd apis/websocket
+
+    # Discord bot
+    cd bots/discord
+
+    # Programmatic API
+    cd packages/api
+
+    # Etc.
+    ```
+
+## ⏭️ What's next
+
+You'll need to go to the respective project's documentation to continue.