Some wording changes and markup fixes

Doc/lib/libsmtplib.tex

@@ -32,12 +32,12 @@ included below.
                         local_hostname\optional{,
                         keyfile\optional{,
                         certfile}}}}}}
-A \class{SMTP_SSL} instance behaves exactly the same as instance \class{SMTP}.
-\class{SMTP_SSL} should be used for the situations where SSL is required from 
-the beginning of the connection and \method{starttls()} is not appropriate.
-If host is not specified, the local host is used. If port is
-omitted, the standard SMTP-over-SSL port (465) is used. keyfile and certfile
-are also optional - they can contain a PEM formatted private key and
+A \class{SMTP_SSL} instance behaves exactly the same as instances of \class{SMTP}.
+\class{SMTP_SSL} should be used for situations where SSL is required from 
+the beginning of the connection and using \method{starttls()} is not appropriate.
+If \var{host} is not specified, the local host is used. If \var{port} is
+omitted, the standard SMTP-over-SSL port (465) is used. \var{keyfile} and \var{certfile}
+are also optional, and can contain a PEM formatted private key and
 certificate chain file for the SSL connection.
 \end{classdesc}