Refine compliance pipelines introductory text

What does this MR do?

This MR:

• Splits group-level things from project-level things.
• Makes clearer that running project-specific pipelines with compliance pipelines is an option, but requires additional configuration.

Results:

• Before: https://docs.gitlab.com/ee/user/project/settings/#compliance-frameworks
• After: http://main-ee-96332.35.193.151.162.nip.io/ee/user/group/manage.html#compliance-frameworks
• After (project settings): http://main-ee-96332.35.193.151.162.nip.io/ee/user/project/settings/index.html#add-a-compliance-framework-to-a-project

Screenshots:

• Before:
• After:
• Before:
• After:
• Before:
• After (no visual change):

CC @katrinleinweber

Related issues

Closes: #371691 (closed)

Author's checklist

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