derive arguments like this:
#[arg(long)]
pub flag: bool,
were producing option descriptions like this:
--flag=FLAG
FLAG is spurious. It turns out that derive always sets a value name, for
simplicity, even when there are no arguments. Check for this case.
Fixes#4443.
This commit updates the man page renderer to use a relative margin
indent for environment variable text instead of appending to the
existing help text.
Signed-off-by: Orhun Parmaksız <orhunparmaksiz@gmail.com>
Fixes: #3630
