Slow mode for a chat channel

[Moin]

This is a quote from release notes introducing the slow-mode feature

@jomaxro

Topic slow mode

We added a new slow mode for topics that are heating up. Staff can enable slow mode from the topic admin wrench. When enabled, users will have to wait for a staff configured period of time before being able to post again.

@fbpbdmin suggests a similar function for chat channels