Fix typo

Author: RebeccaTamachiro

src/content/docs/dns/concepts.mdx

@@ -21,7 +21,7 @@ Before you can start using the Cloudflare DNS service, you must first have a dom
 
 Very often the same company that offers domain registration also offers web hosting and DNS management.
 
-You can register a domain name at coast through [Cloudflare Registrar](/registrar/). Every domain acquired through Cloudflare Registrar must also use Cloudflare as [primary authoritative DNS](#authoritative-dns).
+You can register a domain name at cost through [Cloudflare Registrar](/registrar/). Every domain acquired through Cloudflare Registrar must also use Cloudflare as [primary authoritative DNS](#authoritative-dns).
 
 ## Nameserver