[Docs] Broken link on Spring MVC Test Integration page

[jang-namu]

Describe the bug
There is a broken link on the Spring MVC Test Integration documentation page. The link to "Spring MVC Test" currently points to a non-existent URL.

To Reproduce

1. Go to https://docs.spring.io/spring-security/reference/servlet/test/mockmvc/index.html
2. Find the link to "Spring MVC Test"
3. Click on the link or observe that it points to https://docs.spring.io/spring-framework/reference/testing/spring-mvc-test-framework.html
4. The link leads to a 404 error page

Expected behavior
The link should point to the correct Spring MVC Test documentation page, which appears to be at: https://docs.spring.io/spring-framework/reference/testing/mockmvc.html
I think it was https://docs.spring.io/spring/reference/6.1/testing/spring-mvc-test-framework.html and it changed at recently updated version.