Added link in the doc.

doc/library/tensor/basic.txt

@@ -1187,12 +1187,14 @@ Gradient / Differentiation
     :returns: gradients of the cost with respect to each of the `wrt` terms
 
 
+.. _R_op_list:
 
-R op
-====
 
+List of Implemented R op
+========================
 
-See the tutorial for the R op documentation.
+
+See the :ref:`gradient tutorial <tutcomputinggrads>` for the R op documentation.
 
 list of ops that support R-op:
  * with test [Most is tensor/tests/test_rop.py]

doc/tutorial/gradients.txt

@@ -200,6 +200,7 @@ you need to do something similar to this:
 >>> f([[1,1],[1,1]], [[2,2,],[2,2]], [0,1])
 array([ 2.,  2.])
 
+:ref:`List <R_op_list>` of Op that implement Rop.
 
 L-operator
 ----------