Remove old sandbox option in list and mark as experimental

docs/api/browser-window.md

@@ -226,10 +226,12 @@ It creates a new `BrowserWindow` with native properties as set by the `options`.
       Node global symbols back to the global scope. See example
       [here](process.md#event-loaded).
     * `sandbox` Boolean (optional) - If set, this will sandbox the renderer
-      associated with the window, making it compatible with chromium sandbox and
-      disabling the node.js engine. This is not the same as the
-      `nodeIntegration` option and the APIs available to the preload script are
-      more limited. Read more about the option [here](sandbox-option.md).
+      associated with the window, making it compatible with the Chromium
+      OS-level sandbox and disabling the Node.js engine. This is not the same as
+      the `nodeIntegration` option and the APIs available to the preload script
+      are more limited. Read more about the option [here](sandbox-option.md).
+      **Note:** This option is currently experimental and may change or be
+      removed in future Electron releases.
     * `session` [Session](session.md#class-session) (optional) - Sets the session used by the
       page. Instead of passing the Session object directly, you can also choose to
       use the `partition` option instead, which accepts a partition string. When
@@ -287,7 +289,6 @@ It creates a new `BrowserWindow` with native properties as set by the `options`.
       window. Defaults to `false`. See the
       [offscreen rendering tutorial](../tutorial/offscreen-rendering.md) for
       more details.
-    * `sandbox` Boolean (optional) - Whether to enable Chromium OS-level sandbox.
     * `contextIsolation` Boolean (optional) - Whether to run Electron APIs and
       the specified `preload` script in a separate JavaScript context. Defaults
       to `false`. The context that the `preload` script runs in will still