Fix :: Broken URL link to document

VectorStoreDocumentRetriever not linked so fix it

Signed-off-by: 양예성 <127856153+yeseong0412@users.noreply.github.com>

Author: yeseong0412

spring-ai-docs/src/main/antora/modules/ROOT/pages/api/retrieval-augmented-generation.adoc

@@ -136,7 +136,7 @@ String answer = chatClient.prompt()
         .content();
 ----
 
-See xref:api/retrieval-augmented-generation.adoc#_vectorstoredocumentretriever for more information.
+See xref:api/retrieval-augmented-generation.adoc#_vectorstoredocumentretriever[VectorStoreDocumentRetriever] for more information.
 
 ===== Advanced RAG