docs: update languages and prefixes count

[google-labs-jules]

Updates documentation files (README.md, docs/INSTALL_EN.md, docs/INSTALL_PL.md) to reflect the newly supported 13 languages (from 11) and 53 prefixes (from 52). No functional code was changed.

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PR created automatically by Jules for task 7715601825685677454 started by @dzaczek

[google-labs-jules]

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