DATAJDBC-483 - Fixes small documentation issues.

Add anchor to section on JdbcValue in reference documentation.
Correct the type of `BeforeSaveEvent` in example code.

Original pull request: #189.

src/main/asciidoc/jdbc.adoc

@@ -188,6 +188,7 @@ Converters should be annotated with `@ReadingConverter` or `@WritingConverter` i
 
 `TIMESTAMPTZ` in the example is a database specific data type that needs conversion into something more suitable for a domain model.
 
+[[jdbc.entity-persistence.custom-converters.jdbc-value]]
 ==== JdbcValue
 
 Value conversion uses `JdbcValue` to enrich values propagated to JDBC operations with a `java.sql.Types` type.
@@ -572,7 +573,7 @@ For example, the following listener gets invoked before an aggregate gets saved:
 [source,java]
 ----
 @Bean
-public ApplicationListener<BeforeSave> timeStampingSaveTime() {
+public ApplicationListener<BeforeSaveEvent> timeStampingSaveTime() {
 
 	return event -> {