tweaks

doc/source/codestyle.rst

@@ -84,8 +84,8 @@ For example,
     python -m numpydoc --validate csst_proto.top_level_interface.flip_image
 
 
-Markup language
-===============
+Markup languages
+================
 Markdown and reStructrured Text are two of popular markup languages.
 reStructrured Text is used in Numpydoc docstrings as well as sphinx-based documentation.
 Markdown is much easier and usually used to write `README` for a package.

doc/source/sphinxdoc.rst

-sphinx-based documentation
+Sphinx-based documentation
 ==========================
 
 The sphinx homepage: