Deletes a document referenced by its ID.
DELETE /documents/<documentID>/links/<linkID>
Response type: application/xml or application/json
The response is a message stating the success or failure of the request.
DELETE /documents/8022/links/L4
<success> <message>The resource of type "Link" with identifier "L4" has been successfully removed.</message> <id>L4</id> </success>