Add documentation on how to tun the app locally and how to contribute

[panvicka]

User Story

As a developer or contributor to the project, I want to have clear and comprehensive documentation available so that I can easily run the application locally and contribute effectively to its development.

Acceptance Criteria

• The documentation should provide step-by-step instructions on how to set up the development environment and run the app locally.
• The documentation should cover different operating systems (e.g., Windows, macOS, Linux) to cater to a diverse range of developers.
• It should provide guidelines on coding standards, project structure, and best practices for contributing to the codebase.
• The documentation should include information on the version control system used (e.g., Git) and how to work with branches and pull requests.
• Steps for running automated tests, if applicable, should be part of the documentation.
• The documentation should be written in a clear and understandable language, with examples and illustrations where necessary.