config: Fix -R option

The '-R' is short for '--leave-running', which is a boolean option and
does not require an argument.

From getopt(3) man page:

optstring is a string containing the legitimate option characters. If
such a character is followed by a colon, the option requires an
argument, ...

Signed-off-by: Radostin Stoyanov <rstoyanov1@gmail.com>