Suggestion: Add working example to README

[ErikKalkoken]

As a go beginner I was struggling a bit to get a very simple example to work. One reason might be that there no working example in the README and all the one has to fill in a lot of gaps with the current examples.

To help people get acquainted more easily with this nice library, I would suggest to add this simple example to the README:

package main

import (
	"context"
	"fmt"

	"github.com/antihax/goesi"
)

func main() {
	// create ESI client
	client := goesi.NewAPIClient(nil, "name@example.com")
	// call Status endpoint
	status, _, _ := client.ESI.StatusApi.GetStatus(context.Background(), nil)
	// print current status
	fmt.Println("Players online: ", status.Players)
}

[antihax]

Done, thanks