Add reference to r2dbc database initialization section

Closes gh-20524

Author: snicoll

spring-boot-project/spring-boot-docs/src/docs/asciidoc/spring-boot-features.adoc

@@ -3906,6 +3906,8 @@ TIP: You do not need to specify a driver class name, since Spring Boot obtains t
 NOTE: At least the url should be provided.
 Information specified in the URL takes precedence over individual properties, i.e. `name`, `username`, `password` and pooling options.
 
+TIP: The "`How-to`" section includes a <<howto.adoc#howto-initialize-a-database-using-r2dc, section on how to initialize a database>>.
+
 To customize the connections created by a `ConnectionFactory`, i.e., set specific parameters that you do not want (or cannot) configure in your central database configuration, you can use a `ConnectionFactoryOptionsBuilderCustomizer` `@Bean`.
 The following example shows how to manually override the database port while the rest of the options is taken from the application configuration:
 
@@ -3931,8 +3933,6 @@ The following examples shows how to set some PostgreSQL connection options:
 ----
 
 When a `ConnectionFactory` bean is available, the regular jdbc `DataSource` auto-configuration backs off.
-If you need to initialize or migrate the database on startup, consider using the dedicated Flyway or Liquibase support.
-Alternatively, consider registering a `ResourceDatabasePopulator` bean with the scripts to invoke on startup.