Add missing link to core concepts documentation.

See spring-projects/spring-data-commons#3463

Author: mp911de

src/main/antora/modules/ROOT/pages/repositories/introduction.adoc

@@ -2,7 +2,9 @@
 = Introduction
 :page-section-summary-toc: 1
 
-This chapter explains the basic foundations of Spring Data repositories.
-Before continuing to the LDAP specifics, make sure you have a sound understanding of the basic concepts explained here.
+This chapter explains the basic foundations of Spring Data repositories and LDAP specifics.
+Before continuing to the LDAP specifics, make sure you have a sound understanding of the basic concepts explained in xref:repositories/core-concepts.adoc[Working with Spring Data Repositories].
+
+The goal of the Spring Data repository abstraction is to significantly reduce the amount of boilerplate code required to implement data access layers for various persistence stores.
 
 include::{commons}@data-commons::page$repositories.adoc[leveloffset=+1]