Update README

Author: ninest

Diff for: README.md

@@ -61,6 +61,8 @@ secret = b64encode(random_bytes).decode('utf-8')
 print(secret)
 ```
 
+Note that the encryption is done client-side!
+
 ### Hosting
 
 The game is hosted with Vercel. To host a debug version of the app, run