docs: remove requestHeaders in webRequest.onHeadersReceived (#29932)

Co-authored-by: David Sanders <[email protected]>

docs/api/web-request.md

@@ -154,7 +154,6 @@ response are visible by the time this listener is fired.
     * `timestamp` Double
     * `statusLine` String
     * `statusCode` Integer
-    * `requestHeaders` Record<string, string>
     * `responseHeaders` Record<string, string[]> (optional)
   * `callback` Function
     * `headersReceivedResponse` Object