Replace the example inventory with the fleet

The DO Community placeholder servers are gone. The file now lists the three
hosts the playbooks address by name -- monoco, clair and emily -- under a `web`
group, with the Python 3 interpreter setting kept as an all-hosts var.

No ansible_host is given for any of them: the control node's ~/.ssh/config
already maps each alias to an address, the same convention
prepare-server/inventory documents. Like that file, this one is only read when
it is named explicitly (`-i hosts`) -- Ansible does not discover an inventory by
name.

hosts

@@ -1,24 +1,7 @@
-##########################
-# DO Community Playbooks
-# Example Inventory
-##########################
+[web]
+monoco
+clair
+emily
 
-#########################################################################
-# The "servers" groups is an example of a group with three servers,
-# each identified by a custom alias.
-#########################################################################
-
-[servers]
-server1 ansible_host=174.138.13.97
-server2 ansible_host=188.166.115.68
-server3 ansible_host=188.166.123.245
-
-##########################################################################
-# Makes sure we use Python 3 (/usr/bin/python3) on remote hosts.
-# [servers:vars] sets global values for all nodes in the "servers" group.
-# This is necessary because by default Ansible will try to use
-# /usr/bin/python, which is not available on newer Ubuntu versions.
-#########################################################################
-[servers:vars]
+[all:vars]
 ansible_python_interpreter=/usr/bin/python3
-