Replace minimal \seetext references with better annotated \seerfc

references, telling the reader more about what to expect at the other end
of the links.

Doc/lib/libsmtplib.tex

@@ -75,13 +75,14 @@ A nice selection of exceptions is defined as well:
 
 
 \begin{seealso}
-  \seetext{Internet \rfc{821}, \emph{Simple Mail Transfer Protocol}.
-           Available online at
-           \url{http://info.internet.isi.edu/in-notes/rfc/files/rfc821.txt}.}
-
-  \seetext{Internet \rfc{1869}, \emph{SMTP Service Extensions}.
-           Available online at
-           \url{http://info.internet.isi.edu/in-notes/rfc/files/rfc1869.txt}.}
+  \seerfc{821}{Simple Mail Transfer Protocol}{Protocol definition for
+          SMTP.  This document covers the model, operating procedure,
+          and protocol details for SMTP.}
+  \seerfc{1869}{SMTP Service Extensions}{Definition of the ESMTP
+          extensions for SMTP.  This describes a framework for
+          extending SMTP with new commands, supporting dynamic
+          discovery of the commands provided by the server, and
+          defines a few additional commands.}
 \end{seealso}