feat(cli): add output directory option

src/jcloud_docsgen/cli.py

@@ -30,9 +30,15 @@ def existing_directory(path: str) -> pathlib.Path:
         raise argparse.ArgumentTypeError(f'{_path}: no such file or directory')
     if not path.is_dir():
         raise argparse.ArgumentTypeError(f'{_path}: not a directory')
+    return path
 
 def main() -> int:
     argument_parser = argparse.ArgumentParser()
     argument_parser.add_argument('project_directory', type = existing_directory, nargs = '?', default = pathlib.Path('.'), help = 'The directory of the project')
+    argument_parser.add_argument('-o', '--output-dir', type = pathlib.Path, help = 'the output directory the documentation will be written to')
     args = argument_parser.parse_args()
+
+    if args.output_dir is None:
+        args.output_dir = args.project_directory / 'docs/reference'
+
     return 0