Fix typo in spring-boot-features.adoc

See gh-16213

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

@@ -6613,7 +6613,7 @@ specific slices>> of an application.
 
 TIP: If you are using JUnit 4, don't forget to also add `@RunWith(SpringRunner.class)` to
 your test, otherwise the annotations will be ignored. If you are using JUnit 5, there's no
-need to add the equivalent `@ExtendWith(SpringExtension)` as `@SpringBootTest` and the
+need to add the equivalent `@ExtendWith(SpringExtension.class)` as `@SpringBootTest` and the
 other `@…Test` annotations are already annotated with it.
 
 By default, `@SpringBootTest` will not start a server. You can use the `webEnvironment`