docs: update online examples

Author: oyyd

README.md

@@ -36,6 +36,8 @@ Note that `SOCK_SEQPACKET` sockets don't work on MacOS.
 
 ### Example
 
+[Online Example](https://codesandbox.io/s/node-unix-seqpacket-socket-n3hd8l?file=/index.js)
+
 ```js
 const { SeqpacketServer, SeqpacketSocket } = require('node-unix-socket');
 const os = require('os');
@@ -71,6 +73,8 @@ client.connect(bindPath, () => {
 
 ### Example
 
+[Online Example](https://codesandbox.io/s/node-unix-dgram-socket-76cyyu?file=/index.js)
+
 ```js
 const { DgramSocket } = require('node-unix-socket');
 const os = require('os');
@@ -121,6 +125,8 @@ Note that `SO_REUSEPORT` might behave much differently across operating systems.
 
 ### Example
 
+[Online Http Server Example](https://codesandbox.io/s/node-so-reuseport-net-server-no9mvm?file=/index.js)
+
 ```js
 const { createReuseportFd } = require('node-unix-socket');
 const { Server, Socket } = require('net');