Update README #15

Description

The current README needs to be updated to reflect the 1.0.0 release state: updated installation instructions, feature overview, badges (CI, PyPI version, Python versions), and links to the full documentation.

Current behavior

• README may reference outdated installation methods or missing features.
• No CI/PyPI badges.
• Missing or incomplete quick-start example.

Expected behavior

• Clear project description and feature highlights.
• Badges: PyPI version, Python versions, CI status, license.
• Installation instructions (pip install ModuleTester).
• Minimal quick-start example (create ini, add # guitest: show, run).
• Links to full documentation, changelog, and contribution guide.
• Screenshot or GIF showing the GUI in action.

Acceptance criteria

• Project description is accurate and up-to-date
• Badges are displayed (PyPI, CI, license, Python versions)
• Installation via pip is documented
• Quick-start example is provided (3-5 steps)
• Link to full documentation site
• At least one screenshot of the application