docs: add bootable-containers usage guide

[pcdubs]

Adds documentation for Fedora IoT bootable containers including building custom images, creating bootable devices with bootc-image-builder, deploying to existing systems, and best practices.

[miabbott]

Thanks for starting these docs!

I understand that this content is useful to have in the IoT docs, but I worry that there is a lot of duplication from the upstream or Fedora bootc docs. This means having to keep docs up-to-date in more than one place.

I feel like a lot of the content after the "Deploying to Existing Devices" section gets into too much detail when you could just point folks to the upstream docs.

[pcdubs]

I understand that this content is useful to have in the IoT docs, but I worry that there is a lot of duplication from the upstream or Fedora bootc docs. This means having to keep docs up-to-date in more than one place.

I think there is value in showing iot specific examples and an overview.

I feel like a lot of the content after the "Deploying to Existing Devices" section gets into too much detail when you could just point folks to the upstream docs.

Thanks, I don't disagree and yanked out the best practices and troubleshooting sections. I think its a bit better now, wdyt?

[miabbott]

I still have some reservations about duplicating documentation from elsewhere, but I'll take the "disagree and commit" approach.

[jvanbrunschot]

Thanks for starting these docs; with the following disk-customization you will get a working partition table:

    "disk": {
      "type": "dos",
      "start_offset": "3 MiB",
      "partitions": [
        {
          "fs_type": "vfat",
          "label": "ESP",
          "type": "plain",
          "part_type": "06",
          "minsize": "96 MiB",
          "mountpoint": "/boot/efi"
        },
        {
          "fs_type": "ext4",
          "label": "boot",
          "type": "plain",
          "minsize": "500 MiB",
          "mountpoint": "/boot"
        }
      ]
    }

Currently, this hack is needed to get the firmware etc on the right place, hopefully they merge this soon coreos/bootupd#935