add resolving DNS conflict section

Author: ethanpalm

advanced/subpath/cloudflare.mdx

@@ -79,3 +79,10 @@ async function handleRequest(request) {
 
 Select `Deploy` and wait for the changes to propagate (it can take up to a few
 hours).
+
+## Resolving DNS conflicts
+
+If your domain already points to another service, you will see an error about an existing DNS record. Your Cloudflare Worker must be configured to control all traffic for your domain.
+
+1. Delete the existing DNS record for your domain. See [Delete DNS records](https://developers.cloudflare.com/dns/manage-dns-records/how-to/create-dns-records/#delete-dns-records) in the Cloudflare documentation for more information.
+2. Return to your Worker and add your custom domain.