fix: fixed the type of `WebviewTag.webpreferences` (#42275)

fix: fixed the type of WebviewTag.webpreferences

docs/api/structures/web-preferences.md

@@ -143,6 +143,7 @@
   contain the layout of the document—without requiring scrolling. Enabling
   this will cause the `preferred-size-changed` event to be emitted on the
   `WebContents` when the preferred size changes. Default is `false`.
+* `transparent` boolean (optional) - Whether to enable background transparency for the guest page. Default is `true`. **Note:** The guest page's text and background colors are derived from the [color scheme](https://developer.mozilla.org/en-US/docs/Web/CSS/color-scheme) of its root element. When transparency is enabled, the text color will still change accordingly but the background will remain transparent.
 
 [chrome-content-scripts]: https://developer.chrome.com/extensions/content_scripts#execution-environment
 [runtime-enabled-features]: https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/platform/runtime_enabled_features.json5

docs/api/webview-tag.md

@@ -221,9 +221,7 @@ windows. Popups are disabled by default.
 ```
 
 A `string` which is a comma separated list of strings which specifies the web preferences to be set on the webview.
-The full list of supported preference strings can be found in [BrowserWindow](browser-window.md#new-browserwindowoptions). In addition, webview supports the following preferences:
-
-* `transparent` boolean (optional) - Whether to enable background transparency for the guest page. Default is `true`. **Note:** The guest page's text and background colors are derived from the [color scheme](https://developer.mozilla.org/en-US/docs/Web/CSS/color-scheme) of its root element. When transparency is enabled, the text color will still change accordingly but the background will remain transparent.
+The full list of supported preference strings can be found in [BrowserWindow](browser-window.md#new-browserwindowoptions).
 
 The string follows the same format as the features string in `window.open`.
 A name by itself is given a `true` boolean value.