参加帖子活动
<blockquote>
<p>[POST] /join</p>
</blockquote>
<h3>request</h3>
<pre><code>{
"userID": int,
"articleID": int,
}</code></pre>
<h3>response</h3>
<pre><code>{
"success": bool, // 1代表登录成功
"data": {
"joinNum": int,
},
"code": [状态码],
"msg": String
}</code></pre>