`autoreact`: Manage the automatic reaction system.

    You must have the Manage Emojis permission to interact with the system.

    All phrases that are reacted to are case-insensitive. To prevent confusion
    when commands add reactions of their own, automatic reactions are disabled
    on messages that are commands and messages from the bot itself.

    **Usage:**
        `autoreact add phrase emoji`: Register `phrase` so that any messages
            that contain it are automatically reacted to with `emoji`.
        `autoreact remove phrase`: Stop `phrase` from being automatically
            reacted to.
        `autoreact list`: List all phrases that are automatically reacted to
            and what emoji is associated with them.