DATAJDBC-405 - Fixes asciidoctor includes.

Includes from Spring Data Commons failed because they where made relative from the asciidoc documents.
But the documents get moved before asciidoc is executed.

Corrected the environment variable used for building the reference to account for this.
Removed one manual fix which breaks with the proper fix.

src/main/asciidoc/index.adoc

@@ -4,7 +4,7 @@ Jens Schauder, Jay Bryant, Mark Paluch, Bastian Wilhelm
 :revdate: {localdate}
 :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-data-commons-docs: ../../../../../spring-data-commons/src/main/asciidoc
 :spring-framework-docs: https://docs.spring.io/spring-framework/docs/{springVersion}/
 
 (C) 2018-2019 The original authors.

src/main/asciidoc/jdbc.adoc

@@ -613,7 +613,7 @@ The following table describes the available events:
 
 WARNING: Lifecycle events depend on an `ApplicationEventMulticaster`, which in case of the `SimpleApplicationEventMulticaster` can be configured with a `TaskExecutor`, and therefore gives no guarantees when an Event is processed.
 
-include::../{spring-data-commons-docs}/entity-callbacks.adoc[leveloffset=+1]
+include::{spring-data-commons-docs}/entity-callbacks.adoc[leveloffset=+1]
 
 [[jdbc.entity-callbacks]]
 === Store-specific EntityCallbacks