Add mention of cloud-init support for NTP

Add honorable mention of cloud-init support for NTP to linux/time-sync.md

Author: Jack Williams

articles/virtual-machines/linux/time-sync.md

@@ -136,6 +136,43 @@ For more information about chrony, see [Using chrony](https://access.redhat.com/
 
 On SUSE and Ubuntu releases before 19.10, time sync is configured using [systemd](https://www.freedesktop.org/wiki/Software/systemd/). For more information about Ubuntu, see [Time Synchronization](https://help.ubuntu.com/lts/serverguide/NTP.html). For more information about SUSE, see Section 4.5.8 in [SUSE Linux Enterprise Server 12 SP3 Release Notes](https://www.suse.com/releasenotes/x86_64/SUSE-SLES/12-SP3/#InfraPackArch.ArchIndependent.SystemsManagement).
 
+### cloud-init
+
+Images that use cloud-init to provision the VM can use the ntp section to setup a time sync service. An example of cloud-init installing chrony and configuring it to use the PTP clock source for Ubuntu VMs:
+
+```yaml
+#cloud-config
+ntp:
+  enabled: true
+  ntp_client: chrony
+  config:
+    confpath: /etc/chrony/chrony.conf
+    packages:
+     - chrony
+    service_name: chrony
+    template: |
+       ## template:jinja
+       driftfile /var/lib/chrony/chrony.drift
+       logdir /var/log/chrony
+       maxupdateskey 100.0
+       refclock PHC /dev/ptp_hyperv poll 3 dpoll -2
+       makestep 1.0 -1
+```
+
+You can then base64 the above cloud-config for use in the `osProfile` section in an ARM template:
+
+```powershell
+[Convert]::ToBase64String((Get-Content -Path ./cloud-config.txt -Encoding Byte))
+```
+
+```json
+"osProfile": {
+  "customData": "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"
+}
+```
+
+For more information about cloud-init on Azure, see [Overview of cloud-init support for Linux VMs in Azure](./using-cloud-init.md).
+
 ## Next steps
 
 For more information, see [Accurate time for Windows Server 2016](/windows-server/networking/windows-time-service/accurate-time).