Improved README with better example

cmd/example/main.go

@@ -0,0 +1,28 @@
+package main
+
+import (
+	"context"
+	"io"
+	"log"
+	"os"
+
+	"github.com/wader/goutubedl"
+)
+
+func main() {
+	result, err := goutubedl.New(context.Background(), "https://www.youtube.com/watch?v=jgVhBThJdXc", goutubedl.Options{})
+	if err != nil {
+		log.Fatal(err)
+	}
+	downloadResult, err := result.Download(context.Background(), "best")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer downloadResult.Close()
+	f, err := os.Create("output")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer f.Close()
+	io.Copy(f, downloadResult)
+}