New section header style.

Fix up a few synopses.
diff --git a/Doc/lib/libsocket.tex b/Doc/lib/libsocket.tex
index 47a2914..c6476b9 100644
--- a/Doc/lib/libsocket.tex
+++ b/Doc/lib/libsocket.tex
@@ -1,4 +1,5 @@
-\section{Built-in Module \module{socket}}
+\section{\module{socket} ---
+         Low-level networking interface.}
 \declaremodule{builtin}{socket}
 
 \modulesynopsis{Low-level networking interface.}