Propose edits to DuckDNS docs (home-assistant#5181)

* Propose reorder of config variables

I've found this docs horribly confusing. `lets_encrypt.accept_terms` should appear at the top of the list as it's the first entered variable. Also this should become `required` as typically `optional` config variables are not displayed in the example config, but it is here.

* Update duckdns.markdown

* Minor changes

Author: robmarkcole

source/_addons/duckdns.markdown

@@ -26,10 +26,10 @@ featured: true
 
 Configuration variables:
 
+- **lets_encrypt.accept_terms** (*Optional*): If you accept the [Let's Encrypt Subscriber Agreement][le], it will generate and update Let's Enrypt certificates for your DuckDNS domain.
 - **token** (*Required*): Your Duck DNS API key.
 - **domains** (*Required*): A list of domains to update DNS.
-- **seconds** (*Optional*): Seconds between updates to Duck DNS.
-- **lets_encrypt.accept_terms** (*Optional*): If you accept the [Let's Encrypt Subscriber Agreement][le], it will generate & update Let's Enrypt certificates for your DuckDNS domain.
+- **seconds** (*Required*): Seconds between updates to Duck DNS.
 
 [le]: https://letsencrypt.org/repository/
 
@@ -51,3 +51,5 @@ If you use a port other than `8123` or an SSL proxy, change the port number acco
 You'll need to forward the port you listed in your configuration (8123 in the example above) on your router to your Home Assistant system. You can find guides on how to do this on [Port Forward](https://portforward.com/) - noting that you'll only need to forward the TCP port.
 
 Ensure that you allocate the Home Assistant system a fixed IP on your network before you configure port forwarding. You can do this either on the computer itself (see the [install guide](/hassio/installation/) or via a static lease on your router.
+
+Restart Home Assistant for the configured changes to take effect. When you access the Home Assistant frontend you will now need to use `https`, even when accessing local instances, for example at `https://192.168.0.1:8123`.