#494 - Fix links to Spring-Framework reference docs.

Original pull request: #495.

Author: michael-simons

src/main/asciidoc/index.adoc

@@ -5,7 +5,7 @@
 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-data-r2dbc-javadoc: https://docs.spring.io/spring-data/r2dbc/docs/{version}/api
-:spring-framework-ref: https://docs.spring.io/spring/docs/{springVersion}/spring-framework-reference
+:spring-framework-ref: https://docs.spring.io/spring/docs/{springVersion}/reference/html
 :reactiveStreamsJavadoc: https://www.reactive-streams.org/reactive-streams-{reactiveStreamsVersion}-javadoc
 :example-root: ../../../src/test/java/org/springframework/data/r2dbc/documentation
 :tabsize: 2