Update README.md (#975)

Co-authored-by: Max Isom <[email protected]>

README.md

@@ -31,6 +31,9 @@ Muse is written in TypeScript. You can either run Muse with Docker (recommended)
 - `SPOTIFY_CLIENT_ID` and `SPOTIFY_CLIENT_SECRET` can be acquired [here](https://developer.spotify.com/dashboard/applications) with 'Create a Client ID'.
 - `YOUTUBE_API_KEY` can be acquired by [creating a new project](https://console.developers.google.com) in Google's Developer Console, enabling the YouTube API, and creating an API key under credentials.
 
+> [!WARNING]
+> Even if you don't plan on using Spotify, you must still provide the client ID and secret; otherwise Muse will not function.
+
 Muse will log a URL when run. Open this URL in a browser to invite Muse to your server. Muse will DM the server owner after it's added with setup instructions.
 
 A 64-bit OS is required to run Muse.