Added Sections to What's New

Closes gh-9596

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

@@ -12,9 +12,26 @@ Below are the highlights of the release.
 ** Added https://github.com/spring-projects/spring-security/pull/9535[Jwt Bearer Authorization Grant] support
 ** Added https://github.com/spring-projects/spring-security/pull/8765[R2DBC implementation] of `ReactiveOAuth2AuthorizedClientService`
 
+* OAuth 2.0 Resource Server
+
+** Enhanced JWT decoders https://github.com/spring-projects/spring-security/issues/7160[derivation of signature algorithms]
+** Improved https://github.com/spring-projects/spring-security/issues/9100[content negotation]
+** Improved https://github.com/spring-projects/spring-security/issues/9186[multi-tenancy support]
+
+* 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
+** Enhanced relying party metadata https://github.com/spring-projects/spring-security/issues/9317[support]
+** Added support for https://github.com/spring-projects/spring-security/issues/9177[AP-specified signing methods]
+
 * Configuration
 
 ** Introduced https://github.com/spring-projects/spring-security/issues/9205[DispatcherType request matcher]
+** Introduced https://github.com/spring-projects/spring-security/issues/8900[`AuthorizationManager`] and applied it to filter and https://github.com/spring-projects/spring-security/issues/9289[method security]
 
 * Kotlin DSL
 
@@ -24,3 +41,12 @@ Below are the highlights of the release.
 === WebFlux
 
 ** Added https://github.com/spring-projects/spring-security/issues/8143[Kotlin coroutine support] for `EnableReactiveMethodSecurity`
+
+[[whats-new-build]]
+=== Build
+
+The build has been modernized in a number of different ways.
+Here are a couple of highlights:
+
+* All sample applications have been moved to https://github.com/spring-projects/spring-security-samples[a separate project]
+* The full build now https://github.com/spring-projects/spring-security/issues/9419[works with JDK 11]