Added support of multiple dataset

/*When you want to use dataSet directly, you can specify multiple data to single ExcelSheet with following structure,
//i.e You can have multiple dataSets on Multiple Sheets in Single Excel File
interface {
        xSteps?: number; //How many cells to skips from left (Optional)
        ySteps?: number; //How many rows to skips from last data (Optional)
        columns: [array | string] //array (required)
        data: [array_of_array | string|boolean|number] //array of arrays (required)
    }
*/
import React from "react"
import {default as ExcelFile, ExcelSheet} from "react-data-export"

const multiDataSet = [
    {
        columns: ["Name", "Salary", "Sex"],
        data: [
            ["Johnson", 30000, "Male"],
            ["Monika", 355000, "Female"],
            ["Konstantina", 20000, "Female"],
            ["John", 250000, "Male"],
            ["Josef", 450500, "Male"],
        ]
    },
    {
        xSteps: 1, // Will start putting cell with 1 empty cell on left most
        ySteps: 5, //will put space of 5 rows,
        columns: ["Name", "Department"],
        data: [
            ["Johnson", "Finance"],
            ["Monika", "IT"],
            ["Konstantina", "IT Billing"],
            ["John", "HR"],
            ["Josef", "Testing"],
        ]
    }
];

class App extends React.Component {
    render() {
        return (
            <ExcelFile>
                <ExcelSheet dataSet={multiDataSet} name="Organization" />
                <!-- You can add more ExcelSheets if you need -->
            </ExcelFile>
        );
    }
}