update: readme

Author: amirhnajafiz

README.md

@@ -1,2 +1,29 @@
-# port-scanner
-Fast API for scanning ports of a host.
+<h1 align="center">
+Port Scanner
+</h1>
+
+<p align="center">
+Fast library for scanning ports of a host
+</p>
+
+## How to use?
+You need to give a host address and port range, after that the scanner will 
+check the ports and returns the open ports.
+```go
+package main
+
+import (
+	"fmt"
+
+	scanner "github.com/amirhnajafiz/port-scanner"
+)
+
+func main() {
+    // creating scanner with URI, Port Range, Number of workers (optional, default is 100)
+	openports := scanner.Scan("", 2048)
+
+	for _, port := range openports {
+		fmt.Printf("%d open\n", port)
+	}
+}
+```

example/main.go

@@ -7,7 +7,7 @@ import (
 )
 
 func main() {
-	openports := scanner.Scan("", 2048, 100)
+	openports := scanner.Scan("", 2048)
 
 	for _, port := range openports {
 		fmt.Printf("%d open\n", port)

scanner.go

@@ -9,7 +9,12 @@ import (
 // Scan takes a uri, portRange and number of workers and will
 // test the uri ports in portRange (0, portRange) with workers and then
 // returns the open ports.
-func Scan(uri string, portRange int, numberOfWorkers int) []int {
+func Scan(uri string, portRange int, workers ...int) []int {
+	numberOfWorkers := 100
+	if len(workers) > 0 {
+		numberOfWorkers = workers[0]
+	}
+
 	ports := make(chan int, numberOfWorkers)
 	response := make(chan int)