[Lvfs-announce] Setting the firmware protocol in the metainfo file

I've just updated the LVFS with some new functionality that allows it
to store the update protocol for a specific firmware. This will be
used in the future for both security UI and also for some upload-time
checks so it's important to include as metadata for new uploads. The
update format can either be set in the metainfo.xml file, or can be
set on the LVFS web console. I appreciate that it's nearly Christmas,
and so any firmware that is uploaded without the update protocol isn't
yet prevented from moving to stable. In early 2019, it will be a hard
requirement and listed as a "problem" in the firmware details view.

To include this, just add the following line to new metainfo files:

<custom>
  <value key="LVFS::UpdateProtocol">org.uefi.capsule</value>
</custom>

The list of available protocols can be found here:
https://fwupd.org/lvfs/docs/metainfo/protocol

If anyone has any problems or questions please let me know.

Richard