update README

README.md

@@ -29,13 +29,13 @@
 <a href="https://chrome.google.com/webstore/detail/github-red-issues/kjbbjibfgnnfdeabgmbieapkhpojikpc"><img alt="Opera" width="48" valign="middle" src="https://raw.githubusercontent.com/KatsuteDev/GitHub-Red-Issues/main/assets/opera.svg"></a>
 <a href="https://chrome.google.com/webstore/detail/github-red-issues/kjbbjibfgnnfdeabgmbieapkhpojikpc"><img alt="Chrome Web Store" valign="middle" src="https://img.shields.io/chrome-web-store/v/kjbbjibfgnnfdeabgmbieapkhpojikpc?label=%20&style=flat-square&color=4285F4"></a>
 
-#### Firefox*
+#### Firefox
+
+<sup><i>requires Firefox 121 or higher</i></sup>
 
 <a href="https://addons.mozilla.org/firefox/addon/github-red-issues"><img alt="Mozilla Firefox" width="48" valign="middle" src="https://raw.githubusercontent.com/KatsuteDev/GitHub-Red-Issues/main/assets/firefox.svg"></a>
 <a href="https://addons.mozilla.org/firefox/addon/github-red-issues"><img alt="Mozilla Add-on" valign="middle" src="https://img.shields.io/amo/v/github-red-issues?label=%20&style=flat-square&color=FF7139"></a>
 
-<small>* <code>layout.css.has-selector.enabled</code> must be enabled in <code>about:config</code></small>
-
 ### Changes
 
 Reverts closed issues from purple to red on: