Fix broken links in documentation.

Closes #954
Original pull request #1109

src/main/asciidoc/index.adoc

@@ -5,7 +5,7 @@ Jens Schauder, Jay Bryant, Mark Paluch, Bastian Wilhelm
 :javadoc-base: https://docs.spring.io/spring-data/jdbc/docs/{revnumber}/api/
 ifdef::backend-epub3[:front-cover-image: image:epub-cover.png[Front Cover,1050,1600]]
 :spring-data-commons-docs: ../../../../../spring-data-commons/src/main/asciidoc
-:spring-framework-docs: https://docs.spring.io/spring-framework/docs/{springVersion}/
+:spring-framework-docs: https://docs.spring.io/spring-framework/docs/{springVersion}/reference/html
 
 (C) 2018-2021 The original authors.
 

src/main/asciidoc/preface.adoc

@@ -13,13 +13,13 @@ The rest of the document refers only to Spring Data JDBC features and assumes th
 [[get-started:first-steps:spring]]
 == Learning Spring
 
-Spring Data uses Spring framework's https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/core.html[core] functionality, including:
+Spring Data uses Spring framework's {spring-framework-docs}/core.html[core] functionality, including:
 
-* https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/core.html#beans[IoC] container
+* {spring-framework-docs}/core.html#beans[IoC] container
-* https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/core.html#validation[type conversion system]
+* {spring-framework-docs}/core.html#validation[type conversion system]
-* https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/core.html#expressions[expression language]
+* {spring-framework-docs}/core.html#expressions[expression language]
-* https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/integration.html#jmx[JMX integration]
+* {spring-framework-docs}/integration.html#jmx[JMX integration]
-* https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference/data-access.html#dao-exceptions[DAO exception hierarchy].
+* {spring-framework-docs}/data-access.html#dao-exceptions[DAO exception hierarchy].
 
 While you need not know the Spring APIs, understanding the concepts behind them is important.
 At a minimum, the idea behind Inversion of Control (IoC) should be familiar, and you should be familiar with whatever IoC container you choose to use.