doc: clarify event.isTrusted text

PR-URL: #36827
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

doc/api/events.md

@@ -1338,10 +1338,10 @@ This is not used in Node.js and is provided purely for completeness.
 added: v14.5.0
 -->
 
-* Type: {boolean} True for Node.js internal events, false otherwise.
+* Type: {boolean}
 
-Currently only `AbortSignal`s' `"abort"` event is fired with `isTrusted`
-set to `true`.
+The {AbortSignal} `"abort"` event is emitted with `isTrusted` set to `true`. The
+value is `false` in all other cases.
 
 #### `event.preventDefault()`
 <!-- YAML