Use slash to display menu and filter commands

Signed-off-by: Émile Ré <emile@getprobo.com>

packages/ui/src/RichEditor/MenuButton.tsx

@@ -1,3 +1,7 @@
+// Copyright (c) 2026 Probo Inc <hello@getprobo.com>.
+// Use of this source code is governed by the ISC license
+// that can be found in the LICENSE file.
+
 import type { PropsWithChildren } from "react";
 import { tv } from "tailwind-variants";