Fix link on end-to-end quick start guide doc

What does this MR do?

Backport https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14668.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• Documentation created/updated or follow-up review issue created
• [-] Code review guidelines
• [-] Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• [-] Separation of EE specific content