New section header style.

Fix up a few synopses.
diff --git a/Doc/lib/libthreading.tex b/Doc/lib/libthreading.tex
index 928b422..d2c5ff3 100644
--- a/Doc/lib/libthreading.tex
+++ b/Doc/lib/libthreading.tex
@@ -1,4 +1,5 @@
-\section{Standard Module \module{threading}}
+\section{\module{threading} ---
+         Higher-level threading interfaces.}
 \declaremodule{standard}{threading}
 
 \modulesynopsis{Higher-level threading interfaces.}