Fix a broken Asciidoctor syntax

Along the way, this commit also fixes a typo.

See gh-18288

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

@@ -6039,8 +6039,8 @@ Testing within a mocked environment is usually faster than running with a full S
 However, since mocking occurs at the Spring MVC layer, code that relies on lower-level Servlet container behavior cannot be directly tested with MockMvc.
 
 For example, Spring Boot's error handling is based on the "`error page`" support provided by the Servlet container.
-This means that, whilst you can test your MVC layer throws and handles exceptions as expected, you cannot directly test that a specific <<#boot-features-error-handling-custom-error-pages, custom error page>> is rendered.
-If you need to tests these lower-level concerns, you can start a fully running server as described in the next section.
+This means that, whilst you can test your MVC layer throws and handles exceptions as expected, you cannot directly test that a specific <<boot-features-error-handling-custom-error-pages, custom error page>> is rendered.
+If you need to test these lower-level concerns, you can start a fully running server as described in the next section.
 ====