A store owner can choose categories in which vendors can place their products.

[AndreiMaz]

Let's add a new boolean property to the "Category" entity that will manage whether a vendor can add products to this category. Its name will be "Restrict from vendors". The hint will be "Check to restrict vendors from adding products to this category. This option is useful when you have multi-vendors enabled in your store". The default value will be "false" (so any vendor can add products to this category)

So once enabled vendors won't see this category on the "Add product" or "Edit product" pages in admin area. Also do not forget to add appropriate validation login to the server-side when saving products submitted by vendors