Docs: Improve content regarding solutions for vulnerabilities (auto remediation)

Proposal

Follow-up issue from gitlab-com/www-gitlab-com!120394 (comment 1294147543)

We need to improve our documentation regarding solutions for vulnerabilities (auto remediation)

That section refers to the auto-remediation functionality, but doesn't name it. And in general it appears the auto-remediation documentation for dependency scanning could use some improvement.