replaced 404 github link

otp/openvpn

@@ -1,6 +1,6 @@
 # Uses google authenticator library as PAM module using a single folder for all users tokens
 # User root is required to stick with an hardcoded user when trying to determine user id and allow unexisting system users
-# See https://github.com/google/google-authenticator/tree/master/libpam#secretpathtosecretfile--usersome-user
+# See https://github.com/google/google-authenticator-libpam#usersome-user
 auth required pam_google_authenticator.so secret=/etc/openvpn/otp/${USER}.google_authenticator user=root
 
 # Accept any user since we're dealing with virtual users there's no need to have a system account (pam_unix.so)