Document danger of first mover advantages

[msporny]

Add an entry to the Security Considerations section that highlights inadvertent "first mover" advantages of one party's trust anchors overwhelming others because they published first. What happens when an actor publishes a useful list and then gets most of the ecosystem to use that list and then uses their control over the list to block new entrants into the market?

[BigBlueHat]

This may be covered in an upcoming threat model document.