translated README.en.md from English to Polish

[VinayakPaka]

#688

This pull request adds a Polish translation of the README file to enhance accessibility for Polish-speaking users and contributors. The following tasks were completed:

Translation: The content of README.en.md has been accurately translated into Polish and saved as README.pl.md in the ./doc/i18n/ directory.
Formatting: All markdown formatting, including headings, lists, links, code blocks, and images, has been preserved to match the original English version.
Links & References: Ensured that all links and references are functional and that any language-specific content reflects Polish.
Consistency: Technical terms and terminology have been consistently translated or kept in English where appropriate.
Review: Although not yet reviewed by a native Polish speaker, efforts were made to ensure the accuracy and cultural appropriateness of the translation.
Next Steps:

Review and feedback are appreciated, particularly from native Polish speakers, to ensure the translation is both accurate and culturally appropriate.
Update project documentation or configuration if needed to include the new Polish README.
Thank you for considering this contribution!

[CLAassistant]

All committers have signed the CLA.

[jelveh]

Thank you for this. I used AI to check the quality and it suggested there are some parts that may sound unnatural to Polish-speaking users but overall it's acceptable quality. I'm going to merge this anyway and wait for comments by Polish-speaking contributors.