saml2Login filterProcessingUrl should be loginProcessingUrl

Closes gh-13417

docs/modules/ROOT/pages/servlet/saml2/login/authentication.adoc

@@ -56,7 +56,7 @@ Java::
 SecurityFilterChain securityFilters(HttpSecurity http) throws Exception {
 	http
         // ...
-        .saml2Login((saml2) -> saml2.filterProcessingUrl("/saml2/login/sso"))
+        .saml2Login((saml2) -> saml2.loginProcessingUrl("/saml2/login/sso"))
         // ...
 
     return http.build();
@@ -72,7 +72,7 @@ fun securityFilters(val http: HttpSecurity): SecurityFilterChain {
 	http {
         // ...
         .saml2Login {
-            filterProcessingUrl = "/saml2/login/sso"
+            loginProcessingUrl = "/saml2/login/sso"
         }
         // ...
     }