docs: Prepare release 0.5.1

Change-Id: I377269e4f510b720a4ab11e480c1d0551a32b56e
Refs: #3859
diff --git a/docs/releases.rst b/docs/releases.rst
index bee9557..9b93c63 100644
--- a/docs/releases.rst
+++ b/docs/releases.rst
@@ -5,6 +5,7 @@
    :hidden:
    :maxdepth: 1
 
+   release-notes/release-notes-0.5.1
    release-notes/release-notes-0.5.0
    release-notes/release-notes-0.4.1
    release-notes/release-notes-0.4.0
@@ -16,6 +17,12 @@
    release-notes/release-notes-0.2.0
    release-notes/release-notes-0.1.0
 
+* **ndn-cxx version 0.5.1**
+  (:doc:`Release Notes <release-notes/release-notes-0.5.1>`, `Documentation <http://named-data.net/doc/ndn-cxx/0.5.1/>`__)
+
+  `src (git) <https://github.com/named-data/ndn-cxx/releases/tag/ndn-cxx-0.5.1>`__,
+  `src (tarball) <http://named-data.net/downloads/nfd-0.5.1.tar.bz2>`__ (`checksum <http://named-data.net/downloads/nfd-0.5.1.tar.bz2.sha256>`__)
+
 * **ndn-cxx version 0.5.0**
   (:doc:`Release Notes <release-notes/release-notes-0.5.0>`, `Documentation <http://named-data.net/doc/ndn-cxx/0.5.0/>`__)