update author

resolvers.js

  Mutation: {
    addAuthor: (root, {name, age, Books}) => {
      const author = new authorModel({name, age, Books})
      return author.save()
    },
    deleteAuthor: (root, {id}) => {
        return authorModel.findOneAndRemove({id: id})
    },
    updateAuthor:(root, {id, name})=> {
        return authorModel.findOneAndUpdate({id:id}, {name})
    }
  }