[new lokad] Add spec for onchain trollbox for tokens
Summary: See trollbox.md for rationale. Would be a good way for token creators to communicate with their users and vice versa.
Test Plan: proofread
Reviewers: #bitcoin_abc, tobias_ruck
Reviewed By: #bitcoin_abc, tobias_ruck
Subscribers: Fabien, tobias_ruck
Differential Revision: https://reviews.bitcoinabc.org/D17046