Missing documentation for FZF_COMPLETION_PATH_OPTS and FZF_COMPLETION_DIR_OPTS

[harrypotterIUP]

Checklist

• I have read through the manual page (man fzf)
• I have searched through the existing issues
• For bug reports, I have checked if the bug is reproducible in the latest version of fzf

Output of fzf --version

0.55.0 (fc69308)

OS

• Linux
• macOS
• Windows
• Etc.

Shell

• bash
• zsh
• fish

Problem / Steps to reproduce

I set fzf default options to ignore symlinks, yet ** shell completion doesn't respect this setting, because walker overwrites it depending on the command in question, which might expect file paths or folder paths as arguments, respectively. This is the same issue as #3778 which introduced FZF_COMPLETION_PATH_OPTS and FZF_COMPLETION_DIR_OPTS, but I only learned about those env vars after finding the issue here on GitHub. They're not mentioned in any docs or man page.