Running gdscript_docs_maker.__main__ on reference.json

**I'm submitting an Issue**

- [x] Bug report.
- [ ] Feature request.

## Bug report ##

**What is the current behavior?**
When running `python3 -m gdscript_docs_maker /godot-project/reference.json` I get the error message:

> opt/homebrew/opt/python@3.11/bin/python3.11: No module named gdscript-docs-maker.__main__; 'gdscript-docs-maker' is a package and cannot be directly executed

**What is the expected behavior?**
The module to run successfully generating the markdown files.

**Tell us the steps to reproduce the bug, and if possible share a minimal demo of the problem.**

1. Generate `reference.json`
2. Run `python3 -m gdscript_docs_maker /godot-project/reference.json`

**My Solution.**

Run `python3 -m gdscript_docs_maker.__main__ /godot-project/reference.json` instead.

## Other ##

**Other information**

Running on macOS 13.5.1 (22G90)
Python version `Python 3.11.6`