channelID - Channel ID where the message is located.messageID - The ID of the message.emoji - ID of the emoji you want the bot to react with. Multiple reactions can be added with more emoji's separated with semicolons (;)
If the emoji is default (😃), then just use the emoji itself.
If the emoji is custom (:eeeee:), then just use the emoji ID.
Example 1: Adds a reaction to the command message in this channel.
Example 2: Adds multiple reactions to a message in the #main-chat channel.