skip non-markdown files, add debug

# at mdl.

for path in "$@"; do

    if [ -f "$path" ]; then

        sed 's/^\[\[_TOC_\]\]/TOC_PLACEHOLDER/' "$path" | markdownlint -

        case "$path" in

            *.md|*.mdwn|*.markdown)

                echo "checking file $path..."

                sed 's/^\[\[_TOC_\]\]/TOC_PLACEHOLDER/' "$path" | markdownlint - ;;

        esac

    else

        echo "checking $path..."

        markdownlint "$path"

    fi

done