Update documentation a bit

docs/ansible.md

@@ -2,6 +2,9 @@
 
 This playbook is meant to be run using [Ansible](https://www.ansible.com/).
 
+Ansible typically runs on your local computer and carries out tasks on a remote server.
+If your local computer cannot run Ansible, you can also run Ansible on some server somewhere (including the server you wish to install to).
+
 
 ## Supported Ansible versions
 

examples/hosts

@@ -1,2 +1,2 @@
 [matrix-servers]
-matrix.<your-domain> ansible_host=<your-server's IP address> ansible_ssh_user=root
+matrix.<your-domain> ansible_host=<your-server's external IP address> ansible_ssh_user=root