md2html: use sane_lists extension

This allows for cleaner nesting semantics and matches github more
closely.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

filters/html-converters/md2html

@@ -301,6 +301,7 @@ markdown.markdownFromFile(
 		"markdown.extensions.fenced_code",
 		"markdown.extensions.codehilite",
 		"markdown.extensions.tables",
+		"markdown.extensions.sane_lists",
 		TocExtension(anchorlink=True)],
 	extension_configs={
 		"markdown.extensions.codehilite":{"css_class":"highlight"}})