Sphinxify the ExtendingLLVM documentation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165371 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/programming.rst b/docs/programming.rst
index e8acc1d..c4eec59 100644
--- a/docs/programming.rst
+++ b/docs/programming.rst
@@ -6,10 +6,11 @@
 .. toctree::
    :hidden:
 
+   Atomics
    CodingStandards
    CommandLine
    CompilerWriterInfo
-   Atomics
+   ExtendingLLVM
    HowToSetUpLLVMStyleRTTI
 
 * `LLVM Language Reference Manual <LangRef.html>`_
@@ -40,7 +41,7 @@
   How to make ``isa<>``, ``dyn_cast<>``, etc. available for clients of your
   class hierarchy.
 
-* `Extending LLVM <ExtendingLLVM.html>`_
+* :ref:`extending_llvm`
 
   Look here to see how to add instructions and intrinsics to LLVM.