update docstring to reflect partitionless disk changes

Signed-off-by: Tai Groot <tai@taigrr.com>

pkg/block/block_linux.go

@@ -179,7 +179,9 @@ func diskWWN(paths *linuxpath.Paths, disk string) string {
 // diskPartitions takes the name of a disk (note: *not* the path of the disk,
 // but just the name. In other words, "sda", not "/dev/sda" and "nvme0n1" not
 // "/dev/nvme0n1") and returns a slice of pointers to Partition structs
-// representing the partitions in that disk
+// representing the partitions in that disk. If a disk has no partitions,
+// it returns information on the disk instead, but the Partition UUID is set
+// to the empty string (since there isn't one.)
 func diskPartitions(ctx *context.Context, paths *linuxpath.Paths, disk string) []*Partition {
 	out := make([]*Partition, 0)
 	path := filepath.Join(paths.SysBlock, disk)