Add use case to block access to bad actors

[csarven]

Some mentions about the notion to block bad actors:

• https://github.com/solid/authorization-panel/issues/111
• https://github.com/solid/authorization-panel/issues/115
• https://csarven.ca/linked-research-decentralised-web#addressing-social-implications
• https://dr.amy.gy/chapter3
• https://github.com/solid/authorization-panel/blob/master/proposals/TrustedAppsReplacement.md
• https://www.w3.org/2001/tag/doc/ethical-web-principles/#community (re initial Solid proposal to adopt Ethical Web Principles: https://lists.w3.org/Archives/Public/public-solid/2019Jun/0000.html )

This is a widely known issue to acknowledge. Plethora of examples and studies out there. Important in many areas: journalism, social web, scholarly communication..