use implicit hyperlink instead of :ref:

docs/source/index.rst

diff --git a/docs/source/index.rst b/docs/source/index.rst
index b3a32cd..d9ed122 100644
--- a/docs/source/index.rst
+++ b/docs/source/index.rst
@@ -119,7 +119,7 @@
            make <module_name>	
         ..
 
-		For an example of hardening a project please refer to :ref:`Hardening the User Project using OpenLane` .
+		For an example of hardening a project please refer to `Hardening the User Project using OpenLane`_. .
 	
 #.  Integrate modules into the user_project_wrapper