Prepare release 0.5.1

Change-Id: I6355c350822fa5de1f68db6d205ca2ba4044b0dc
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index bc26a47..cef5a82 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,6 +1,15 @@
 Release Notes
 =============
 
+## Version 0.5.1
+
+- Fix forceful shutdown of `Face` when destructing `Logic` instance
+  (Issue #4525)
+
+- Fix compilation against the latest version of ndn-cxx library
+
+- Upgrade `waf` to the latest version and other improvements
+
 ## Version 0.5.0
 
 - **Breaking change** Use bzip2 compression of sync Data payload (Issue #4140)