Fix URL of smtpd-pipe

README.md

@@ -9,8 +9,9 @@ Configuration and data storage must be mounted respectively in
 */etc/lurker* and */var/lib/lurker*.
 
 Instead of running a full-blown Postfix instance, this container runs
-a very simple [SMTP server](smtpd.go) that is only suitable for internal
-traffic.
+a very simple [SMTP
+server](https://git.autistici.org/ai3/tools/smtpd-pipe) that is only
+suitable for internal traffic.
 
 The image expects /var/lib/lurker to be mounted externally with the
 right permissions, and to contain the *www* and *data* subdirectories.