feat(python-generator)!: do not require specific structure

Removed all implicit assumptions of a project structure:
  - no 'src/' directory is required
  - top-level modules are no longer ignored

src/jcloud_docsgen/cli/cli.py

@@ -78,6 +78,7 @@ def create_argument_parser() -> argparse.ArgumentParser:
         '-o',
         '--output-dir',
         type=pathlib.Path,
+        default='docs/reference',
         help='the output directory the documentation will be written to',
     )
 
@@ -138,9 +139,6 @@ def main(argv=None) -> int:
     argument_parser = create_argument_parser()
     args = argument_parser.parse_args(argv)
 
-    if args.output_dir is None:
-        args.output_dir = args.project_directory / 'docs/reference'
-
     try:
         if args.language == _LANG_PYTHON:
             from .languages.python import generate