fix typo

Chapter 2/datasource-demo/src/main/resources/application.properties

@@ -4,8 +4,8 @@ spring.output.ansi.enabled=ALWAYS
 spring.datasource.url=jdbc:h2:mem:testdb
 spring.datasource.username=sa
 spring.datasource.password=
-spring.datasource.hikari.maxPoolSize=5
+spring.datasource.hikari.maximumPoolSize=5
-spring.datasource.hikari.minIdle=5
+spring.datasource.hikari.minimumIdle=5
 spring.datasource.hikari.idleTimeout=600000
 spring.datasource.hikari.connectionTimeout=30000
 spring.datasource.hikari.maxLifetime=1800000