Updated project to improve guidance

terraform/cloud-init/network-config.yaml.tpl

@@ -1,3 +1,13 @@
+# cloud-init's network-config schema (distinct from the #cloud-config
+# user-data schema in server.yaml.tpl/agent.yaml.tpl — no "#cloud-config"
+# header here, and `version: 2` picks the netplan-style dialect). eth0 is
+# the interface name libvirt's virtio NIC presents as inside a fresh
+# Ubuntu cloud image — the only interface that exists at boot, since each
+# node has exactly one network_interface in main.tf's libvirt_domain.
+# `nameservers` points at the gateway rather than a public resolver
+# because that's also where libvirt's own DNS forwarder listens (the `dns
+# { enabled = true }` block on libvirt_network.k3s in main.tf) — it
+# resolves both k3s.local addresses and forwards everything else out.
 version: 2
 ethernets:
   eth0: