docs: responseHeaders should be Record<string, string[]> (#21730)

docs/api/web-request.md

@@ -146,7 +146,7 @@ response are visible by the time this listener is fired.
     * `timestamp` Double
     * `statusLine` String
     * `statusCode` Integer
-    * `responseHeaders` Record<string, string> (optional)
+    * `responseHeaders` Record<string, string[]> (optional)
   * `callback` Function
     * `headersReceivedResponse` Object
       * `cancel` Boolean (optional)
@@ -175,7 +175,7 @@ The `callback` has to be called with a `response` object.
     * `resourceType` String
     * `referrer` String
     * `timestamp` Double
-    * `responseHeaders` Record<string, string> (optional)
+    * `responseHeaders` Record<string, string[]> (optional)
     * `fromCache` Boolean - Indicates whether the response was fetched from disk
       cache.
     * `statusCode` Integer
@@ -205,7 +205,7 @@ and response headers are available.
     * `ip` String (optional) - The server IP address that the request was
       actually sent to.
     * `fromCache` Boolean
-    * `responseHeaders` Record<string, string> (optional)
+    * `responseHeaders` Record<string, string[]> (optional)
 
 The `listener` will be called with `listener(details)` when a server initiated
 redirect is about to occur.
@@ -224,7 +224,7 @@ redirect is about to occur.
     * `resourceType` String
     * `referrer` String
     * `timestamp` Double
-    * `responseHeaders` Record<string, string> (optional)
+    * `responseHeaders` Record<string, string[]> (optional)
     * `fromCache` Boolean
     * `statusCode` Integer
     * `statusLine` String