Update MachineRegistration example

[fgiudici]

just update the example with the one described in PR #61

[kkaempf]

The write_files is still unclear to me.
We should place a README next to this file with explanations.
(or can we add comments into the file directly ? 🤩 )

[Itxaka]

The write_files is still unclear to me.

what is unclear? Its a cloud config directive. Whatever is on the cloud-configkey will get dumped into a cloud-config file, so anything valid on a cloud-config file is valid in our cloud-config struct 👍 write_files is exactly: https://cloudinit.readthedocs.io/en/latest/topics/modules.html#write-files

[fgiudici]

Well, just added the path to write_files (I didn't realized I forgot it!) and a comment to highlight what @Itxaka basically wrote here (you can put your cloud-init section of choice)

[kkaempf]

Well, just added the path to write_files

Thanks ! This is what I was missing 😉