New section header style.

Fix up a few synopses.
diff --git a/Doc/lib/libcmath.tex b/Doc/lib/libcmath.tex
index 5337967..d5328e3 100644
--- a/Doc/lib/libcmath.tex
+++ b/Doc/lib/libcmath.tex
@@ -1,4 +1,5 @@
-\section{Built-in Module \module{cmath}}
+\section{\module{cmath} ---
+         Mathematical functions for complex numbers.}
 \declaremodule{builtin}{cmath}