Improve RFC links (#8612)

The `tools.ietf.org` site now redirects to `www.rfc-editor.org`.
* Update various URLs to the new site.
* Make links to `www.rfc-editor.org` consistent.

Signed-off-by: SuperQ <superq@gmail.com>

man/coredns-transfer.7

@@ -1,5 +1,5 @@
 .\" Generated by Mmark Markdown Processer - mmark.miek.nl
-.TH "COREDNS-TRANSFER" 7 "March 2026" "CoreDNS" "CoreDNS Plugins"
+.TH "COREDNS-TRANSFER" 7 "October 2026" "CoreDNS" "CoreDNS Plugins"
 
 .SH "NAME"
 .PP
@@ -28,6 +28,7 @@ use this plugin.
 .nf
 transfer [ZONE...] {
   to ADDRESS...
+  source ADDRESS
 }
 
 .fi
@@ -43,6 +44,10 @@ there must be another plugin in the same server block that serves the same zone,
 addresses. Zone change notifications are sent to all \fBADDRESS\fP that are an IP address or
 an IP address and port e.g. \fB\fC1.2.3.4\fR, \fB\fC12:34::56\fR, \fB\fC1.2.3.4:5300\fR, \fB\fC[12:34::56]:5300\fR.
 \fB\fCto\fR may be specified multiple times.
+.IP \(bu 4
+\fB\fCsource\fR \fBADDRESS\fP is the local IP address to use when sending zone change
+notifications to the configured \fB\fCto\fR addresses. It does not change which
+clients are allowed to request AXFR or IXFR transfers.
 
 
 .PP
@@ -72,6 +77,23 @@ Use in conjunction with the \fIacl\fP plugin to restrict access to subnet 10.1.0
 .fi
 .RE
 
+.PP
+Send NOTIFY messages from a specific local address.
+
+.PP
+.RS
+
+.nf
+\&...
+  transfer {
+    to 2001:db8::1
+    source 2001:db8::53
+  }
+\&...
+
+.fi
+.RE
+
 .PP
 Each plugin that can use \fItransfer\fP includes an example of use in their respective documentation.