Update reverse-proxies.zh-cn.md

[ghost]

add proxy header to nginx config example

        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;

Signed-off-by: rock2dust its@baronbunny.cn

[wxiaoguang]

I haven't looked into the Gitea code to know how these headers work or whether it's the best practice.

Since the English version has been changed by #18922

For document sync purpose, I can LGTM