Adding documentation for link object

Change-Id: Ied40e45296fb25b7efd227e2e13a2af48223ba1b
diff --git a/data.rst b/data.rst
index 39be231..7948bd6 100644
--- a/data.rst
+++ b/data.rst
@@ -48,7 +48,7 @@
 | BLOB            | 0              | payload identified by the data name; this is the default     |
 |                 |                | ContentType                                                  |
 +-----------------+----------------+--------------------------------------------------------------+
-| LINK            | 1              | another name which identifies the actual data content        |
+| LINK            | 1              | a list of delegations (see :ref:`link`)                      |
 +-----------------+----------------+--------------------------------------------------------------+
 | KEY             | 2              | public key                                                   |
 +-----------------+----------------+--------------------------------------------------------------+