Typo in `--openvpn_heuristics` flag in help

[s4n-cz]

Describe the bug

There is a typo in the help in the flag --openvpn_heuristics (missing n). I was preparing a PR, but ended up creating issue because of the Contributor License Agreement, need to read contributing guidelines, etc. That's too much work for a simple typo fix.

[IvanNardi]

@s4n-cz, thanks for reporting this typo