Remove all uses of \sectcode; we can now use logical markup everywhere.
diff --git a/Doc/lib/libmain.tex b/Doc/lib/libmain.tex
index 8ce73a8..df1fbfb 100644
--- a/Doc/lib/libmain.tex
+++ b/Doc/lib/libmain.tex
@@ -1,4 +1,4 @@
-\section{Built-in Module \sectcode{__main__}}
+\section{Built-in Module \module{__main__}}
 \label{module-main}
 \bimodindex{__main__}
 This module represents the (otherwise anonymous) scope in which the