Retrieves a relation for a specified contact if associated with the authenticated client.
curl --request GET \ --url https://api.smokeball.com/contacts/{contactId}/relations/{relatedContactId} \ --header 'Authorization: <api-key>' \ --header 'x-api-key: <api-key>'
{ "id": "<string>", "href": "<string>", "relation": "<string>", "method": "GET" }
When request is successful. Returns a 'Link' object.