New section header style.

Fix up a few synopses.
diff --git a/Doc/lib/libmailbox.tex b/Doc/lib/libmailbox.tex
index 5ebc57d..8110291 100644
--- a/Doc/lib/libmailbox.tex
+++ b/Doc/lib/libmailbox.tex
@@ -1,4 +1,5 @@
-\section{Standard Module \module{mailbox}}
+\section{\module{mailbox} ---
+         Read various mailbox formats.}
 \declaremodule{standard}{mailbox}
 
 \modulesynopsis{Read various mailbox formats.}