update readme

README.md

@@ -1,12 +1,18 @@
 ## node-threads-pool
-nodejs threads pool
+[david-image]: https://img.shields.io/david/pengxigua/node-threads-pool.svg?style=flat-square
+[david-url]: https://david-dm.org/pengxigua/node-threads-pool
+[node-image]: https://img.shields.io/badge/node.js-%3E=_12-green.svg?style=flat-square
+[node-url]: http://nodejs.org/download/
+[download-image]: https://img.shields.io/npm/dm/node-threads-pool.svg?style=flat-square
+[download-url]: https://npmjs.org/package/node-threads-pool
+[license-image]: https://img.shields.io/npm/l/node-threads-pool.svg
 
 ### Install
 ```
 npm install node-threads-pool
 ```
 
-### Example
+### Usage
 ```
 
 //app.js
@@ -33,9 +39,19 @@ tp.run("./thread.js", {
 const {workerData, parentPort} = require("worker_threads");
 const {n} = workerData;
 const fn = (n) => {
- if(n < 3) return n - 1;
+ if(n < 3) return 1;
  return fn(n-2) + fn(n-1);
 }
 parentPort.postMessage(fn(n));
 
-```
+```
+
+### Methods
+
+#### new TP([number]); // number: the maximum number of threads. The default value is 1.
+Create a thread pool instance.
+
+
+#### TP.run(filename[, options]); // options: [View here](https://nodejs.org/dist/latest-v12.x/docs/api/worker_threads.html#worker_threads_new_worker_filename_options)
+
+Run a file in a child thread.

test/app.js

@@ -1,5 +1,5 @@
 const TP = require("../index");
-const tp = new TP(20);
+const tp = new TP(10);
 
 for(var i = 0; i < 1000; i++) {
  tp.run(__dirname + "/thread.js", {

test/thread.js

@@ -1,7 +1,7 @@
 const {workerData, parentPort} = require("worker_threads");
 const {n, index} = workerData;
 const fn = (n) => {
- if(n < 3) return n - 1;
+ if(n < 3) return 1;
  return fn(n-2) + fn(n-1);
 }
 parentPort.postMessage({