docs: fix syntax highlighting of code blocks

And various other cleanups

Change-Id: If945f5407036e73db980cafd2185359a488a0ff1
diff --git a/docs/release-notes/release-notes-0.5.1.rst b/docs/release-notes/release-notes-0.5.1.rst
index cdb555a..8e1acc9 100644
--- a/docs/release-notes/release-notes-0.5.1.rst
+++ b/docs/release-notes/release-notes-0.5.1.rst
@@ -10,8 +10,8 @@
 
 Changes since version 0.5.0:
 
-New features:
-^^^^^^^^^^^^^
+New features
+^^^^^^^^^^^^
 
 - Add version 2 of the security framework (introduced in ``security::v2`` namespace)