To rename a category name in Discord.js, you can use the setName() method on the category object. First, you need to fetch the category using its ID or name. Once you have the category object, you can call the setName() method and pass the new name as a parameter. Make sure you have the necessary permissions to rename the category. After renaming the category, the changes will be reflected in the Discord server.What is the function used to rename a category in discord.js.