docs(serverless-component): update readme with custom domain name instructions (#366)

Co-authored-by: Daniel <danielconde9@gmail.com>

Author: owlas

README.md

@@ -97,7 +97,12 @@ $ serverless
 
 In most cases you wouldn't want to use CloudFront's distribution domain to access your application. Instead, you can specify a custom domain name.
 
-Make sure you've purchased your `domain` within Route53:
+You can use any domain name but you must be using AWS Route53 for your DNS hosting. To migrate DNS records from an existing domain follow the instructions
+[here](https://docs.aws.amazon.com/Route53/latest/DeveloperGuide/MigratingDNS.html). The requirements to use a custom domain name:
+ * Route53 must include a _hosted zone_ for your domain (e.g. `mydomain.com`) with a set of nameservers.
+ * You must update the nameservers listed with your domain name registrar (e.g. namecheap, godaddy, etc.) with those provided for your new _hosted zone_.
+
+The serverless next.js component will automatically generate an SSL certificate and create a new record to point to your CloudFront distribution.
 
 ```yml
 # serverless.yml