Fix issue #1983: Incorrect configuration file path

[github-actions[bot]]

This pull request fixes #1983.

The issue requested changing the configuration file path from emqx/etc/emqx.conf to /etc/emqx/emqx.conf in the specified Markdown file. The provided git patch shows that the line 优化设置 Erlang 虚拟机启动参数，配置文件 etc/emqx.conf: was changed to 优化设置 Erlang 虚拟机启动参数，配置文件 /etc/emqx/emqx.conf:. Although the original text in the file was etc/emqx.conf (missing the emqx/ prefix compared to the issue description's stated original), the critical part of the fix was to update the path to the correct absolute path /etc/emqx/emqx.conf, which the patch successfully accomplished. This directly addresses the core problem described in the issue.

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