New section header style.

Fix up a few synopses.
diff --git a/Doc/lib/libgdbm.tex b/Doc/lib/libgdbm.tex
index 844c3b3..adb1304 100644
--- a/Doc/lib/libgdbm.tex
+++ b/Doc/lib/libgdbm.tex
@@ -1,4 +1,5 @@
-\section{Built-in Module \module{gdbm}}
+\section{\module{gdbm} ---
+         GNU's reinterpretation of dbm.}
 \declaremodule{builtin}{gdbm}
 
 \modulesynopsis{GNU's reinterpretation of dbm.}