restructured library manual accordiung to functional group
diff --git a/Doc/librfc822.tex b/Doc/librfc822.tex
index d819238..e2d182e 100644
--- a/Doc/librfc822.tex
+++ b/Doc/librfc822.tex
@@ -21,6 +21,8 @@
 e.g. \code{m['From']}, \code{m['from']} and \code{m['FROM']} all yield
 the same result.
 
+\subsection{Message Objects}
+
 A \code{Message} instance has the following methods:
 
 \begin{funcdesc}{rewindbody}{}