Fixup broken doc link.  Patch by Sean Silva <silvas@purdue.edu>.

llvm-svn: 160082
diff --git a/llvm/docs/userguides.rst b/llvm/docs/userguides.rst
index 57f77f8..26a5a8c 100644
--- a/llvm/docs/userguides.rst
+++ b/llvm/docs/userguides.rst
@@ -20,7 +20,7 @@
    Everything from unpacking and compilation of the distribution to execution
    of some tools.
     
-* :ref:`cmake`
+* :ref:`building-with-cmake`
 
    An addendum to the main Getting Started guide for those using the `CMake
    build system <http://www.cmake.org>`_.