Get all markdown files.

def _get_md_files(self):
        """Get all markdown files."""
        all_f = _all_files_matching_ext(os.getcwd(), "md")
        exclusions = [
            "*.egg/*",
            "*.eggs/*",
            "*build/*"
        ] + self.exclusions
        return sorted([f for f in all_f if not _is_excluded(f, exclusions)])