To retrieve a list of any "neighbors" (i.e. Droplets that are co-located on
the same physical hardware) for a specific Droplet, send a GET request to
/v2/droplets/$DROPLET_ID/neighbors.
The results will be returned as a JSON object with a key of droplets. This
will be set to an array containing objects representing any other Droplets
that share the same physical hardware. An empty array indicates that the
Droplet is not co-located any other Droplets associated with your account.