add[readme]: update system requirements

Author: amnweb

README.md

@@ -1,4 +1,6 @@
 # Firefox Plus (Windows only)
+> **Note:** FireFox v135+ only
+
 <img src="screenshots/firefox-26-11-2023.jpg" alt="screenshot" title="Screenshot" width="900">
 <img src="screenshots/firefox-25-11-2023.jpg" alt="screenshot" title="Screenshot" width="900">
 <img src="screenshots/Screenshot 2023-12-04 144143.png" alt="screenshot" title="Screenshot" width="900">
@@ -12,8 +14,6 @@
 2. Download and copy the `chrome` folder and `user.js` into the profile folder.
 3. Restart Firefox.
 
-> **Note:** FireFox v135+ only
-
 # Tweaks
 - To enable macOS button style, open `user.js`, find `fp.tweak.macos-button` and set it to `true`.  
 - To disable bookmarks autohide open `user.js`, find `fp.tweak.autohide-bookmarks` and set it to `false`.