Add FreeBSD example for azure-chroot.

examples/azure/freebsd-chroot.json

@@ -0,0 +1,27 @@
+{
+  "variables": {},
+  "builders": [
+    {
+      "type": "azure-chroot",
+      "source": "thefreebsdfoundation:freebsd-12_1:12_1-release:latest",
+      "image_resource_id": "/subscriptions/{{vm `subscription_id`}}/resourceGroups/{{vm `resource_group`}}/providers/Microsoft.Compute/images/freebsd-{{timestamp}}",
+      "os_disk_size_gb": 64,
+      "os_disk_storage_account_type": "Premium_LRS",
+      "mount_partition": 2,
+      "chroot_mounts": [
+        ["devfs", "devfs", "/dev"],
+        ["procfs", "procfs", "/proc"]
+      ]
+    }
+  ],
+  "provisioners": [
+    {
+      "inline": [
+        "env ASSUME_ALWAYS_YES=YES pkg bootstrap",
+        "/usr/local/sbin/waagent -force -deprovision+user && export HISTSIZE=0 && sync"
+      ],
+      "inline_shebang": "/bin/sh -x",
+      "type": "shell"
+    }
+  ]
+}