updated petclinic README

Signed-off-by: Pranshu Srivastava <iampranshu24@gmail.com>

Author: PranshuSrivastava

spring-petclinic/spring-petclinic-rest/src/main/resources/application-postgresql.properties

@@ -11,6 +11,6 @@ spring.datasource.password=petclinic
 spring.datasource.driver-class-name=org.postgresql.Driver
 spring.jpa.database=POSTGRESQL
 spring.jpa.database-platform=org.hibernate.dialect.PostgreSQLDialect
-spring.jpa.hibernate.ddl-auto=create
+spring.jpa.hibernate.ddl-auto=update
 #----------------------------------------------------------------
 # PostgreSQL config end