Polish database docs section

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -171,7 +171,7 @@ content into your application; rather pick only the properties that you need.
 	spring.datasource.platform= # the platform to use in the schema resource (schema-${platform}.sql)
 	spring.datasource.continueOnError=false # continue even if can't be initialized
 	spring.datasource.separator=; # statement separator in SQL initialization scripts
-	spring.datasource.driverClassName= # JDBC Settings...
+	spring.datasource.driver-class-name= # JDBC Settings...
 	spring.datasource.url=
 	spring.datasource.username=
 	spring.datasource.password=

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

@@ -1258,12 +1258,15 @@ in `application.properties`:
 	spring.datasource.url=jdbc:mysql://localhost/test
 	spring.datasource.username=dbuser
 	spring.datasource.password=dbpass
-	spring.datasource.driverClassName=com.mysql.jdbc.Driver
+	spring.datasource.driver-class-name=com.mysql.jdbc.Driver
 ----
 
 See {sc-spring-boot-autoconfigure}/jdbc/DataSourceProperties.{sc-ext}[`DataSourceProperties`]
 for more of the supported options.
 
+TIP: You often won't need to specify the `driver-class-name` since Spring boot can deduce
+it for most databases from the `url`.
+
 NOTE: For a pooling `DataSource` to be created we need to be able to verify that a valid
 `Driver` class is available, so we check for that before doing anything. I.e. if you set
 `spring.datasource.driverClassName=com.mysql.jdbc.Driver` then that class has to be