encourage using 'basename' always with --

[bittorf]

proposal:

#!/bin/sh
file='-/a/b/c.de'
basename "$file"

this throws an error:

# basename "$file"
basename: invalid option -- '/'
Try 'basename --help' for more information.

so better remind the use to always call with

basename -- "$file"

maybe related: #9 and
https://unix.stackexchange.com/questions/94295/shellcheck-is-advising-not-to-use-basename-why/381440

[tripleee]

As already commented on the PR, this is by no means specific to basename, and so the check should probably be extended to any command which accepts a file name parameter. basename is a common victim to this because people do

for filename in *; do
    basename "$filename"
done

but the proper fix here is to say

for filename in ./*; do