Hello Jessica, Ben here - your Shopify Guru!
I hope you already figured this out but after creating a link list for your vendors you could add a drop down menu to your main menu for the list of your vendors. To do this you would just add a main menu link with the same name as your vendor list. Or you can edit the vendor list handle to be the same as the menu item you wish to have the vendor list drop down from.
We have documentation on how drop down menus work here:
https://docs.shopify.com/manual/your-website/navigation/create-drop-down-menu
I hope this helps! Feel free to reach out if you have any further questions :)
Cheers,
Ben C - Shopify Guru
Support@Shopify.com