Fixes dead link to security-essentials

Benjamin Ansohn McDougallrequested to merge
gitlab-community/gitlab-org/gitlab:update-outdated-security-essentials into master

A link within the Documentation isn't leading to the desired result, but rather to a not-found site on university.gitlab.com.

security-essentials on Tutorial is broken.

I think it should lead to: Fixed Link which seems to be a new judging from the assigned Tag next to it.

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