Fix error messages in argparse examples (GH-6435)


The examples in argparse documentation use `error: too few arguments`
error message which was removed in this commit f97c59a in 2011.
(cherry picked from commit 04e82934659487ecae76bf4a2db7f92c8dbe0d25)

Co-authored-by: suic86 <marko.gabriel.cz@gmail.com>
1 file changed