更新关于备用ssh端口的文档

连接: https://docs.gitlab.cn/ee/user/jihulab_com/index.html#%E5%A4%87%E7%94%A8-ssh-%E7%AB%AF%E5%8F%A3

内容修改如下:

JihuLab.com can be reached by using a different SSH port for git+ssh.

Setting	Value
Hostname	altssh.jihulab.com
Port	443

An example ~/.ssh/config is the following:

Host jihulab.com
  Hostname altssh.jihulab.com
  User git
  Port 443
  PreferredAuthentications publickey

需要进行翻译一下，这是global的内容进行修改后的内容