clarify highlight_language conf option

Author: shati-patel

docs/codeql/conf.py

@@ -39,7 +39,9 @@
 # The name of the Pygments (syntax highlighting) style to use.
 pygments_style = 'sphinx'
 
-# The default language for syntax highlighting, defaults to Python if omitted.
+# The default language for syntax highlighting. We need to explicitly set this to "none",
+# otherwise Sphinx tries to highlight any unlabeled code samples as "python3".
+# See https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-highlight_language.
 
 highlight_language = "none"