Fix #6536 (#6558)

.env.production.sample

@@ -183,7 +183,7 @@ STREAMING_CLUSTER_NUM=1
 # Optional SAML authentication (cf. omniauth-saml)
 # SAML_ENABLED=true
 # SAML_ACS_URL=
-# SAML_ISSUER=http://localhost:3000/auth/auth/saml/metadata
+# SAML_ISSUER=http://localhost:3000/auth/auth/saml/callback
 # SAML_IDP_SSO_TARGET_URL=https://idp.testshib.org/idp/profile/SAML2/Redirect/SSO
 # SAML_IDP_CERT=
 # SAML_IDP_CERT_FINGERPRINT=