Fix:#3329 Fixed Developer Setup Link in install.rst

Author: RaunakJalan

doc/users/install.rst

@@ -116,7 +116,7 @@ NeuroDocker_.
 Installation for developers
 ---------------------------
 
-Developers should start `here <../devel/testing_nipype.html>`_.
+Developers should start `here <../devel/testing_nipype.rst>`_.
 
 Developers can also use this docker container: `docker pull nipype/nipype:master`