Improve documentation

Author: nullhack

README.md

@@ -134,7 +134,7 @@ Don't forget to give the project a star! Thanks again!
 <!-- LICENSE -->
 ## License
 
-Distributed under the MIT License. See [`LICENSE.txt`](https://github.com/nullhack/cookiecutter-python-base-project/blob/master/LICENSE.txt) for more information.
+Distributed under the MIT License. See [`LICENSE.txt`](https://github.com/nullhack/cookiecutter-python-base-project/blob/main/LICENSE.txt) for more information.
 
 <p align="right">(<a href="#top">back to top</a>)</p>
 
@@ -177,4 +177,4 @@ References and sources of inspiration
 [issues-shield]: https://img.shields.io/github/issues/nullhack/cookiecutter-python-base-project.svg?style=for-the-badge
 [issues-url]: https://github.com/nullhack/cookiecutter-python-base-project/issues
 [license-shield]: https://img.shields.io/badge/license-MIT-green?style=for-the-badge
-[license-url]: https://github.com/nullhack/cookiecutter-python-base-project/blob/master/LICENSE.txt
+[license-url]: https://github.com/nullhack/cookiecutter-python-base-project/blob/main/LICENSE.txt

{{cookiecutter.project_slug}}/README.md

@@ -200,7 +200,7 @@ Don't forget to give the project a star! Thanks again!
 <!-- LICENSE -->
 ## License
 
-Distributed under the {{cookiecutter.license}} License. See [`LICENSE.txt`](https://github.com/{{cookiecutter.github_username}}/{{cookiecutter.project_slug}}/blob/master/LICENSE.txt) for more information.
+Distributed under the {{cookiecutter.license}} License. See [`LICENSE.txt`](https://github.com/{{cookiecutter.github_username}}/{{cookiecutter.project_slug}}/blob/main/LICENSE.txt) for more information.
 
 <p align="right">(<a href="#top">back to top</a>)</p>
 
@@ -245,5 +245,5 @@ References and sources of inspiration
 [issues-shield]: https://img.shields.io/github/issues/{{cookiecutter.github_username}}/{{cookiecutter.project_slug}}.svg?style=for-the-badge
 [issues-url]: https://github.com/{{cookiecutter.github_username}}/{{cookiecutter.project_slug}}/issues
 [license-shield]: https://img.shields.io/badge/license-{{cookiecutter.license}}-green?style=for-the-badge
-[license-url]: https://github.com/{{cookiecutter.github_username}}/{{cookiecutter.project_slug}}/blob/master/LICENSE.txt
+[license-url]: https://github.com/{{cookiecutter.github_username}}/{{cookiecutter.project_slug}}/blob/main/LICENSE.txt
 

{{cookiecutter.project_slug}}/docs/uml/artifacts/.gitignore

@@ -1 +1,4 @@
+# Ignore everything in this directory
 *
+# Except this file
+!.gitignore