update docs/uniCloud/_sidebar.md.

更新qq群

docs/uniCloud/_sidebar.md

@@ -96,7 +96,8 @@
 	  <div>uniCloud QQ交流群</div>
 	  <div>群1：1012245137 (2000人已满)</div>
     <div>群2：749911289 (1000人已满)</div>
-    <div>群3：599819864 &nbsp;<a target="_blank" href="//qm.qq.com/cgi-bin/qm/qr?k=5iPtQlJt8cxKSwHEpMqcdDYwDX8Xk0dR&jump_from=webapi">点此加入</a></div>
+<div>群3：599819864 (1000人已满)</div>
+    <div>群4：641753405 &nbsp;<a target="_blank" href="https://qm.qq.com/cgi-bin/qm/qr?k=n8Qk7gMN-ppFly_vE9_S34hLNXz25PVI&jump_from=webapi">点此加入</a></div>
 	  </div>
 	</div>
   <div class="contact-item">