The path of "sysctl.conf" is wrong in README_zh.md

[xffish]

In section of "How to turn off TCP BBR".The original text is

Edit the "/mnt/etc/sysctl.conf" file, execute the command "sysctl -p" to view the results, and do not see the following comments, representing the operation succeeded.

But the real path is /etc/sysctl.conf, is it a just typo?The same problem is also exist on Chinese translation.

[aiminick]

Fixed, THK for report.