Update "Configure Commotion" with info on opening port 443 in Firewall

[andygunn]

Update Configure Commotion with the following text and screenshots (with highlighting):

By default, Commotion prevents access to the administration web
interface from a node's ethernet port, because sometimes this port will
be connected directly to the internet. Preventing access to the admin
portal from the internet helps keep unwanted intruders from damaging the
node and other parts of the network.

However, in some advanced network configurations, you'll need to access
the administration web interface over a node's ethernet port. This may
be the case if the node is configured to mesh over ethernet, or when the
node is attached to a common ethernet switch with other nodes.

If this is the case, you can add a rule to the node's firewall in order
to access the admin portal over the node's ethernet interface. You'll
begin by connecting to the node's wireless access point, and going to
http://thisnode in your browser.

1. Click on the Administration button on the bottom of the page.
2. Go to Advanced->Network->Firewall.
3. At the top of the page, click on the "Traffic Rules" tab.
4. Under the "Open ports on router" section, you'll fill in the
   following values:
   a. Name: "Admin interface"
   b. Protocol: "TCP"
   c. External port: 443
5. Click the "Add" button next to the fields you just filled out.
6. Click on "Save & Apply" at the bottom of the page.

[andygunn]

Content created, will create a pull request for getting it into Staging.