PTR reminder, name

docs/INSTALL-digital-ocean.md

@@ -46,6 +46,8 @@ You will be asked for permission to connect, type `yes`, then the root password,
 
 # Install Docker
 
+Update to a newer kernel:
+
     apt-get update
     apt-get install linux-image-generic-lts-raring linux-headers-generic-lts-raring
 
@@ -111,6 +113,7 @@ We renamed `DISCOURSE_HOSTNAME` to `discourse.techapj.com`, this means that we w
 
 - Don't forget to set the [SPF and DKIM records](http://help.mandrill.com/entries/21751322-What-are-SPF-and-DKIM-and-do-I-need-to-set-them-up-) up for your domain name. In Mandrill, that's under Sending Domains, View DKIM/SPF setup instructions.
 
+- The name of your droplet is your reverse PTR record, so rename your droplet to `forum.example.com` so the PTR record correctly reflects your domain name.
 
 # Add Your SSH Key