docs: fix syntax highlighting of code blocks

And various other cleanups

Change-Id: If945f5407036e73db980cafd2185359a488a0ff1
diff --git a/docs/release-notes/release-notes-0.3.1.rst b/docs/release-notes/release-notes-0.3.1.rst
index 7f8a9f0..e48b00d 100644
--- a/docs/release-notes/release-notes-0.3.1.rst
+++ b/docs/release-notes/release-notes-0.3.1.rst
@@ -5,8 +5,8 @@
 
 Changes since version 0.3.0:
 
-New features:
-^^^^^^^^^^^^^
+New features
+^^^^^^^^^^^^
 
 - **Management**
 
@@ -17,8 +17,8 @@
 
   - Add CachingPolicy to ``LocalControlHeader`` (:issue:`2183`)
 
-Updates and bug fixes:
-^^^^^^^^^^^^^^^^^^^^^^
+Updates and bug fixes
+^^^^^^^^^^^^^^^^^^^^^
 
 - **Wire encoding**
 
@@ -51,8 +51,8 @@
   - Explicitly define ``_GLIBCXX_USE_NANOSLEEP``, necessary for gcc < 4.8 in some environments
     (:issue:`2499`)
 
-Removed:
-^^^^^^^^
+Removed
+^^^^^^^
 
 - Delete deprecated ``Block(std::istream&)`` constructor (:issue:`2241`)