Translate README.md from English to Finnish

[jelveh]

We need to create a Finnish version of our README to make our project more accessible to Finnish-speaking users and contributors.

Task Description

• Translate the content of ./doc/i18n/README.en.md to Finnish
• Create a new file ./doc/i18n/README.fi.md with the translated content
• Ensure the format and styling of the original English README is preserved exactly in the Finnish version

Steps

1. Copy the existing README.en.md file to create README.fi.md in the same directory (./doc/i18n/)
2. Translate all text content from English to Finnish, including:
   • Headings
   • Paragraphs
   • Lists
   • Code comments (if any)
   • Any other textual content
3. Preserve all markdown formatting, including:
   • Heading levels
   • Bold and italic text
   • Links
   • Code blocks
   • Tables
   • Images
4. Ensure all links and references remain functional in the Finnish version
5. Update any language-specific content (e.g., language badges) to reflect Finnish instead of English

Additional Considerations

• Maintain consistent terminology throughout the translation
• Pay attention to technical terms that may have specific translations or may need to remain in English
• If there are any culture-specific examples or references, consider adapting them for a Finnish-speaking audience if appropriate

Definition of Done

• README.fi.md file created in ./doc/i18n/ directory
• All content accurately translated to Finnish
• Format and styling match the original English version exactly
• All links and references are functional
• Translation reviewed by a native Finnish speaker (if possible)
• Update project documentation or configuration to include the new Finnish README (if necessary)

Resources

• Original English README: ./doc/i18n/README.en.md
• GitHub Markdown Guide for reference on markdown syntax