What's new and migrating are prominently featured

Before this commit those were burried in the Appendix where few would
guess to look. Previously that information was at the top, so it makes
sense to point to the Github wiki from the index HTML page.

Also a general update of the index page. Since we have recently revised
the overview, we can simply point to it and keep it shorter.

The section listing now includes more details per section.

src/docs/asciidoc/appendix.adoc

@@ -7,18 +7,6 @@
 :toclevels: 2
 :docinfo1:
 
-[[spring-whats-new]]
-== What's New in the Spring Framework
-"What's New" guides for releases of the Spring Framework are now provided as a
-link:{wiki-spring-framework}/++What's-New-in-the-Spring-Framework++[Wiki page].
-
-
-[[migration-4.x]]
-== Migrating to Spring Framework 4.3 / 5.0
-Migration guides for upgrading from previous releases of the Spring Framework are now provided as a
-{wiki-spring-framework}/Migrating-from-earlier-versions-of-the-spring-framework[Wiki page].
-
-
 [[annotation-programming-model]]
 == Spring Annotation Programming Model
 Spring's annotation programming model is documented in the

src/docs/asciidoc/index.adoc

@@ -3,36 +3,27 @@ The Spring Framework team and contributors https://github.com/spring-projects/sp
 :doc-root: https://docs.spring.io
 :api-spring-framework: {doc-root}/spring-framework/docs/{spring-version}/javadoc-api/org/springframework
 
-
-The Spring Framework is a lightweight solution and a potential one-stop-shop for
-building your enterprise-ready applications. However, Spring is modular, allowing you to
-use only those parts that you need, without having to bring in the rest. You can use the
-IoC container, with any web framework on top, but you can also use only the
-<<data-access.adoc#orm-hibernate,Hibernate integration code>> or the
-<<data-access.adoc#jdbc-introduction,JDBC abstraction layer>>. The Spring Framework supports declarative
-transaction management, remote access to your logic through RMI or web services, and various
-options for persisting your data.
-It offers full-featured web frameworks such as <<web.adoc#mvc,Spring Web MVC>>
-and <<web-reactive.adoc#webflux, Spring WebFlux>>; and it enables you to
-integrate <<core.adoc#aop-introduction,AOP>> transparently into your software.
-
-This document is a reference guide to Spring Framework features. Questions on the
-Framework itself should be asked on StackOverflow (see https://spring.io/questions[]).
-
-This reference document provides the following sections:
-
-* <<overview.adoc#spring-introduction,Overview of the Spring Framework>>
-
-* <<core.adoc#spring-core,Core concepts such as IoC and AOP>>
-
-* <<testing.adoc#testing,Testing with Spring>>
-
-* <<data-access.adoc#spring-data-tier,Data access and transaction management>>
-
-* The Web on <<web.adoc#spring-web,Servlet>> or <<web-reactive.adoc#spring-webflux,Reactive>> stacks
-
-* <<kotlin.adoc#kotlin,Kotlin support>>
-
-* <<integration.adoc#spring-integration,Integration with other technologies>>
-
-* <<appendix.adoc#spring-appendices,Appendix>>
+Welcome to the Spring Framework reference!
+
+Please read the <<overview.adoc,Overview>> for an introduction including brief history,
+design philosophy, where to ask questions, and tips to get started. For information on
+what's new, or migrating from a previous version, check the
+https://github.com/spring-projects/spring-framework/wiki[Github Wiki].
+
+The reference is divided into several sections:
+
+[horizontal]
+<<core.adoc#spring-core,Core>> :: IoC container, Events, Resources, i18n, Validation,
+Data Binding, Type Conversion, SpEL, AOP.
+<<testing.adoc#testing,Testing>> :: Mock objects, TestContext framework,
+Spring MVC Test, WebTestClient.
+<<data-access.adoc#spring-data-tier,Data Access>> :: Transactions, DAO support, JDBC,
+ORM, Marshalling XML.
+<<web.adoc#spring-web,Web Servlet>> :: Spring MVC web framework, WebSocket,
+SockJS, STOMP messaging.
+<<web-reactive.adoc#spring-webflux,Web Reactive>> :: Spring WebFlux,
+WebClient, WebSocket support.
+<<integration.adoc#spring-integration,Integration>> :: Remoting, JMS, JCA, JMX, Email,
+Tasks, Scheduling, Cache, Dynamic languages.
+<<kotlin.adoc#kotlin,Kotlin>> :: Extensions, Bean Definition DSL, WebFlux DSL
+<<appendix.adoc#spring-appendices,Appendix>> :: XML Schemas, JSP Tag Libraries

src/docs/asciidoc/overview.adoc

@@ -1,6 +1,7 @@
 :toc: left
 :toclevels: 1
 :docinfo1:
+
 = Spring Framework Overview
 
 Spring makes it easy to create Java enterprise applications. It provides everything you
@@ -19,6 +20,7 @@ Spring is open source. It has a large and active community that provides continu
 based on a diverse range of real-world use cases. This has helped Spring to successfully
 evolve over a very long time.
 
+[[overview-spring]]
 == What We Mean by "Spring"
 
 The term "Spring" means different things in different contexts. It can be used to refer to
@@ -41,6 +43,7 @@ A note about modules: Spring's framework jars allow for deployment to JDK 9's mo
 the same naming pattern with "-" instead of ".", e.g. "spring-core" and "spring-context").
 Of course, Spring's framework jars keep working fine on the classpath on both JDK 8 and 9.
 
+[[overview-history]]
 == History of Spring and the Spring Framework
 
 Spring came into being in 2003 as a response to the complexity of the early
@@ -81,6 +84,7 @@ among others. It’s important to remember that each project has its own source
 issue tracker, and release cadence. See https://spring.io/projects[spring.io/projects] for
 the complete list of Spring projects.
 
+[[overview-philosophy]]
 == Design Philosophy
 
 When you learn about a framework, it’s important to know not only what it does but what
@@ -103,6 +107,7 @@ that are intuitive and that hold up across many versions and many years.
 meaningful, current, and accurate Javadoc. It is one of very few projects that can claim
 clean code structure with  no circular dependencies between packages.
 
+[[overview-feedback]]
 == Feedback and Contributions
 
 For how-to questions or diagnosing or debugging issues, we suggest using StackOverflow,
@@ -122,6 +127,7 @@ information that is not specific to any one version. For example, it has migrati
 notes from earlier versions, comprehensive information on what's new across multiple
 versions, contributor guidelines, the Spring Framework code style, and other information.
 
+[[overview-getting-started]]
 == Getting Started
 
 If you are just getting started with Spring, you may want to begin using the Spring