build: bump ndn-cxx dependency

Change-Id: Ieb71a4f72bb59e4df08113743d27f5d3c299af44
diff --git a/docs/index.rst b/docs/index.rst
index 3a40dfc..9886f33 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -1,6 +1,12 @@
 NAC: Name-Based Access Control
 ==============================
 
+.. toctree::
+   :hidden:
+   :maxdepth: 3
+
+   spec
+
 NAC is a C++ library providing Name-Based Access control primitives that
 can be used to implement content confidentiality in NDN applications.
 
@@ -10,17 +16,11 @@
 Documentation
 -------------
 
-.. toctree::
-   :hidden:
-   :maxdepth: 3
-
-   spec
-
 - :doc:`spec`
-- `API documentation (doxygen) <doxygen/annotated.html>`_
+- `API documentation (doxygen) <doxygen/annotated.html>`__
 
 License
 -------
 
 NAC is an open source project licensed under the LGPL version 3. For more information about
-the license, refer to `COPYING.md <https://github.com/named-data/name-based-access-control/blob/new/COPYING.md>`_.
+the license, refer to `COPYING.md <https://github.com/named-data/name-based-access-control/blob/new/COPYING.md>`__.