Adding doc for the new API introduced by elastic#64517 - /_security/saml/metadata/{realm}

Related to elastic#49018

Author: BigPandaToo

x-pack/docs/build.gradle

@@ -56,7 +56,7 @@ testClusters.integTest {
   setting 'xpack.security.authc.realms.pki.pki1.certificate_authorities', '[ "testClient.crt" ]'
   setting 'xpack.security.authc.realms.pki.pki1.delegation.enabled', 'true'
   setting 'xpack.security.authc.realms.saml.saml1.order', '4'
-  setting 'xpack.security.authc.realms.saml.saml1.sp.logout', 'https://kibana.example.com/logout'
+  setting 'xpack.security.authc.realms.saml.saml1.sp.logout', 'https://kibana.org/logout'
   setting 'xpack.security.authc.realms.saml.saml1.idp.entity_id', 'https://my-idp.org'
   setting 'xpack.security.authc.realms.saml.saml1.idp.metadata.path', 'idp-docs-metadata.xml'
   setting 'xpack.security.authc.realms.saml.saml1.sp.entity_id', 'https://kibana.org'

x-pack/docs/en/rest-api/security/saml-sp-metadata.asciidoc

@@ -15,7 +15,7 @@ Generate SAML metadata for a SAML 2.0 Service Provider.
 The SAML 2.0 specification provides a mechanism for Service Providers to
 describe their capabilities and configuration using a metadata file. This API
 generates Service Provider metadata, based on the configuration of a SAML realm
-in Elasticsearch.
+in {es}.
 
 [[security-api-saml-sp-metadata-path-params]]
 ==== {api-path-parms-title}
@@ -39,11 +39,11 @@ SAML realm `saml1`:
 --------------------------------------------------
 GET /_security/saml/metadata/saml1
 --------------------------------------------------
-The API returns the following response:
+The API returns the following response containing the SAML metadata as an XML string:
 
 [source,console-result]
 --------------------------------------------------
 {
-    "metadata" : "<?xml version=\"1.0\" encoding=\"UTF-8\"?><md:EntityDescriptor xmlns:md=\"urn:oasis:names:tc:SAML:2.0:metadata\" entityID=\"https://kibana.org\"><md:SPSSODescriptor AuthnRequestsSigned=\"false\" WantAssertionsSigned=\"true\" protocolSupportEnumeration=\"urn:oasis:names:tc:SAML:2.0:protocol\"><md:SingleLogoutService Binding=\"urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect\" Location=\"https://kibana.example.com/logout\"/><md:AssertionConsumerService Binding=\"urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST\" Location=\"https://kibana.org/api/security/saml/callback\" index=\"1\" isDefault=\"true\"/></md:SPSSODescriptor></md:EntityDescriptor>"
+    "metadata" : "<?xml version=\"1.0\" encoding=\"UTF-8\"?><md:EntityDescriptor xmlns:md=\"urn:oasis:names:tc:SAML:2.0:metadata\" entityID=\"https://kibana.org\"><md:SPSSODescriptor AuthnRequestsSigned=\"false\" WantAssertionsSigned=\"true\" protocolSupportEnumeration=\"urn:oasis:names:tc:SAML:2.0:protocol\"><md:SingleLogoutService Binding=\"urn:oasis:names:tc:SAML:2.0:bindings:HTTP-Redirect\" Location=\"https://kibana.org/logout\"/><md:AssertionConsumerService Binding=\"urn:oasis:names:tc:SAML:2.0:bindings:HTTP-POST\" Location=\"https://kibana.org/api/security/saml/callback\" index=\"1\" isDefault=\"true\"/></md:SPSSODescriptor></md:EntityDescriptor>"
 }
 --------------------------------------------------