Removed SAML SLO from What's New

Issue gh-9596

docs/manual/src/docs/asciidoc/_includes/about/whats-new.adoc

@@ -21,7 +21,6 @@ Below are the highlights of the release.
 * SAML 2.0 Service Provider
 
 ** Added https://github.com/spring-projects/spring-security/issues/9095[OpenSAML 4 support]
-** Added https://github.com/spring-projects/spring-security/issues/8731[Single Logout support]
 ** Enhanced SAML 2.0 https://github.com/spring-projects/spring-security/issues/9131[Assertion] https://github.com/spring-projects/spring-security/issues/9044[decryption]
 ** Added https://github.com/spring-projects/spring-security/issues/9028[file-based configuration] for asserting party metadata
 ** Improved https://github.com/spring-projects/spring-security/issues/9486[`RelyingPartyRegistration` resolution] support