link to rpki-client.org, which already saw two portable releases;

suggested by Alexander underscore Naumov at opensuse dot org

Author: ischwarze

index.html

@@ -101,6 +101,7 @@ <h2>
       Associated projects:
       <a href="https://www.openssh.com">OpenSSH</a>,
       <a href="http://www.openbgpd.org">OpenBGPD</a>,
+      <a href="https://www.rpki-client.org">rpki-client</a>,
       <a href="http://www.openntpd.org">OpenNTPD</a>,
       <a href="https://www.opensmtpd.org">OpenSMTPD</a>,
       <a href="openiked/index.html">OpenIKED</a>,