Remove all uses of \sectcode; we can now use logical markup everywhere.
diff --git a/Doc/lib/libmath.tex b/Doc/lib/libmath.tex
index 6cbf830..1cc6b20 100644
--- a/Doc/lib/libmath.tex
+++ b/Doc/lib/libmath.tex
@@ -1,4 +1,4 @@
-\section{Built-in Module \sectcode{math}}
+\section{Built-in Module \module{math}}
 \label{module-math}
 
 \bimodindex{math}