Use the new RFC macros wherever RFCs are referenced by number.  No other
changes.
diff --git a/Doc/lib/libbase64.tex b/Doc/lib/libbase64.tex
index e764737..8ad10c8 100644
--- a/Doc/lib/libbase64.tex
+++ b/Doc/lib/libbase64.tex
@@ -2,12 +2,12 @@
 \label{module-base64}
 \stmodindex{base64}
 \indexii{base-64}{encoding}
-\index{RFC!1421}
+\rfcindex{1421}
 \index{MIME!base 64 encoding}
 
 This module perform base-64 encoding and decoding of arbitrary binary
 strings into text strings that can be safely emailed or posted.  The
-encoding scheme is defined in RFC 1421 and is used for MIME email and
+encoding scheme is defined in \rfc{1421} and is used for MIME email and
 various other Internet-related applications; it is not the same as the
 output produced by the \file{uuencode} program.  For example, the
 string \code{'www.python.org'} is encoded as the string