Update files/en-us/mozilla/firefox/releases/139/index.md

Co-authored-by: Brian Smith <brian@smith.berlin>

Author: hamishwillee

files/en-us/mozilla/firefox/releases/139/index.md

@@ -51,7 +51,7 @@ This article provides information about the changes in Firefox 139 that affect d
 #### Removals
 
 - The experimental {{svgelement("discard")}} element has been removed, along with its corresponding {{domxref("SVGDiscardElement")}} JavaScript interface.
-  These aren't in other browsers and are expected to be removed from the specification.
+  These aren't supported in other browsers and are expected to be removed from the specification.
   ([Firefox bug 1958839](https://bugzil.la/1958839)).
 
 ### HTTP