Optional: Using DO Databases instead of Droplet volumes

[RicoFio]

Hi DO curators,

While this might not fall into the main focus of this Supabase DO template, it might be worth adding documentation on how people can setup their Supabase on DO while using the dedicated DO Databases product rather than relying on volumes on Droplets. This is also something that is encouraged by the official Supabase docs here.