updated ikev1/xauth-rsa scenario to xauth plugin

testing/tests/ikev1/xauth-rsa/description.txt

@@ -1,7 +1,9 @@
 The roadwarriors <b>carol</b> and <b>dave</b> set up a connection to gateway <b>moon</b>.
 The authentication is based on RSA signatures (<b>RSASIG</b>) using X.509 certificates
 followed by extended authentication (<b>XAUTH</b>) of <b>carol</b> and <b>dave</b>
-based on user names and passwords.
+based on user names equal to the <b>IKEv1 identity</b> (<b>carol@strongswan.org</b> and
+<b>dave@strongswan.org</b>, respectively) and corresponding user passwords defined and
+stored in ipsec.secrets.
 <p>
 Upon the successful establishment of the IPsec tunnel, leftfirewall=yes automatically
 inserts iptables-based firewall rules that let pass the tunneled traffic.