Append sentence on subdomain setup next to PSL reference

Author: RebeccaTamachiro

src/content/partials/fundamentals/add-site.mdx

@@ -13,7 +13,7 @@ import { GlossaryTooltip, Render } from "~/components"
 
    If Cloudflare is unable to identify your domain as a registered domain, make sure you are using an existing [top-level domain](https://www.cloudflare.com/learning/dns/top-level-domain/) (`.com`, `.net`, `.biz`, or others).
 
-   Additionally, Cloudflare requires your `apex domain` to be one level below a valid TLD defined in the [Public Suffix List (PSL)](https://github.com/publicsuffix/list/blob/master/public_suffix_list.dat). 
+   Cloudflare requires your `apex domain` to be one level below a valid TLD defined in the [Public Suffix List (PSL)](https://github.com/publicsuffix/list/blob/master/public_suffix_list.dat). Enterprise customers can onboard lower-level subdomains using [Subdomain setup](/dns/zone-setups/subdomain-setup/).
    :::
 
 4. Select a [plan](https://www.cloudflare.com/plans/#compare-features).