Add Renovate bot

[thiagolunardi]

This pull request introduces Renovate for automated dependency updates and updates the project documentation to improve clarity and modernize the presentation. The most important changes are grouped below:

Renovate integration:

• Added .github/renovate.json to configure Renovate for NuGet dependencies, including branch naming, author info, and release age rules.
• Added .github/workflows/renovate.yml to enable Renovate as a scheduled GitHub Action using a dedicated token.

Documentation improvements in README.md:

• Refreshed section headings with emojis and improved formatting for better readability and engagement. [1] [2] [3] [4]
• Updated Docker instructions to use modern docker compose commands, clarified folder names, and improved setup steps for both Docker and Visual Studio environments.
• Enhanced project description and motivation, making the purpose and comparison to EShopOnContainers clearer and more concise.