Adds a missing dot

source/webhooks/index.html.md.erb

@@ -34,7 +34,7 @@ Your callback URL must use HTTPS and present a valid certificate. GOV.UK webhook
 
 Your callback URL must have a domain that ends with `.gov.uk`. This restriction does not apply if you're using webhooks on a test service.
 
-We can allow other domains if you cannot host your callback URL on a domain that ends with `gov.uk`. You can ask us to allow a domain by emailing support at [[email protected]](mailto:[email protected]). We'll only allow domains that exclusively belong to your service or your service's parent organisation. If we allow your domain, there'll be a delay before you can use it.
+We can allow other domains if you cannot host your callback URL on a domain that ends with `.gov.uk`. You can ask us to allow a domain by emailing support at [[email protected]](mailto:[email protected]). We'll only allow domains that exclusively belong to your service or your service's parent organisation. If we allow your domain, there'll be a delay before you can use it.
 
 ## Create a webhook