refactor: yml -> yaml

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/node_exporter/tasks/systemd.yaml

@@ -0,0 +1,10 @@
+---
+- name: Ensure node_exporter is running and enabled at boot.
+  ansible.builtin.service:
+    name: node_exporter
+    state: started
+    daemon_reload: true
+    enabled: true
+  notify:
+    - Restart node_exporter
+  become: true