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

Related to elastic#49018

Author: BigPandaToo

x-pack/docs/en/rest-api/security/saml_sp_metadata.asciidoc

@@ -38,6 +38,6 @@ The API returns the following response:
 [source,console-result]
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 {
-    "metadata" : "<?xml version=\"1.0\" encoding=\"UTF-8\"?><md:EntityDescriptor xmlns:md=\"urn:oasis:names:tc:SAML:2.0:metadata\" entityID=\"https://kibana.example.com/\"><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.example.com/api/security/v1/saml\" 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: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>"
 }
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