docs: NSVisualEffectMaterialDark has been deprecated and removed as of macOS 10.15 (#27125)

* NSVisualEffectMaterialDark has been deprecated and removed as of macOS 10.15.

* Update browser-window.md

docs/api/browser-window.md

@@ -238,7 +238,7 @@ It creates a new `BrowserWindow` with native properties as set by the `options`.
     window shadow and window animations. Default is `true`.
   * `vibrancy` String (optional) - Add a type of vibrancy effect to the window, only on
     macOS. Can be `appearance-based`, `light`, `dark`, `titlebar`, `selection`,
-    `menu`, `popover`, `sidebar`, `medium-light`, `ultra-dark`, `header`, `sheet`, `window`, `hud`, `fullscreen-ui`, `tooltip`, `content`, `under-window`, or `under-page`.  Please note that using `frame: false` in combination with a vibrancy value requires that you use a non-default `titleBarStyle` as well. Also note that `appearance-based`, `light`, `dark`, `medium-light`, and `ultra-dark` have been deprecated and will be removed in an upcoming version of macOS.
+    `menu`, `popover`, `sidebar`, `medium-light`, `ultra-dark`, `header`, `sheet`, `window`, `hud`, `fullscreen-ui`, `tooltip`, `content`, `under-window`, or `under-page`.  Please note that using `frame: false` in combination with a vibrancy value requires that you use a non-default `titleBarStyle` as well. Also note that `appearance-based`, `light`, `dark`, `medium-light`, and `ultra-dark` are deprecated and have been removed in macOS Catalina (10.15).
   * `zoomToPageWidth` Boolean (optional) - Controls the behavior on macOS when
     option-clicking the green stoplight button on the toolbar or by clicking the
     Window > Zoom menu item. If `true`, the window will grow to the preferred