Feature summary (what you would like to be able to do and where):
masto-collab should support setting content warnings.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
In some circumstances, posts that accounts like @Wikipedia post might need content warnings. Examples include political issues (for example, the SOPA blackout in the past), or coverage of sensitive topics such as war.