Rename the obsolete term TOST/Trellis with SD-Fabric

Change-Id: I27602bb9004f409f1e64b568a30c84d09f5b958f
diff --git a/index.rst b/index.rst
index a09810b..6fac7d1 100644
--- a/index.rst
+++ b/index.rst
@@ -12,7 +12,7 @@
 at these sites:
 
 * `SD-Core <https://opennetworking.org/sd-core/>`_
-* :doc:`SD-Fabric (Trellis) <trellis:index>`
+* `SD-Fabric <https://opennetworking.org/sd-fabric/>`_
 * `SD-RAN <https://docs.sd-ran.org/master/index.html>`_
 * `Stratum <https://github.com/stratum/stratum/>`_
 * `µONOS <https://docs.onosproject.org/>`_