fix: address Vale style comment on setting-up-your-domain

Co-Authored-By: Devin Logan <devinannlogan@gmail.com>

Author: devin-ai-integration[bot]

fern/products/docs/pages/preview-publish/setting-up-your-domain.mdx

@@ -206,7 +206,7 @@ Errors below are surfaced by `fern check` and `fern generate --docs` when valida
     The `url` is missing a subdomain or uses an unexpected shape. Use `<your-org>.docs.buildwithfern.com` (for example, `plantstore.docs.buildwithfern.com`). Don't include `https://`.
   </Accordion>
   <Accordion title='Invalid domain in URL "X". The URL must end with one of: docs.buildwithfern.com, docs.dev.buildwithfern.com'>
-    The `url` doesn't end with a supported Fern domain. Update the `url` to end with `docs.buildwithfern.com`. Configure your vanity domain separately with `custom-domain`.
+    The `url` doesn't end with a supported Fern domain. Update the `url` to end with `docs.buildwithfern.com`. Configure your vanity domain with `custom-domain`.
   </Accordion>
   <Accordion title='Invalid URL "X". A subdomain is required before docs.buildwithfern.com'>
     The `url` is set to the bare domain. Add a subdomain prefix such as `<your-org>.docs.buildwithfern.com`.
@@ -227,4 +227,4 @@ instances:
 
 <Info>
 After configuring multiple domains in your `docs.yml`, contact Fern via your dedicated Slack channel or [email](mailto:support@buildwithfern.com) to complete the setup. You'll receive DNS configuration details for each domain.
-</Info>                                                
+</Info>