Update _config.yml and add .yml files

_config.yml

_data/lang/pl/footer-1.yml

_data/lang/pl/footer-2.yml

_data/lang/pl/navigation.yml

_data/lang/pl/roadmap.yml

_data/lang/template/footer-1.yml

_i18n/pl.yml

_i18n/pl/community/events.md

_i18n/pl/community/hangouts.md

_i18n/pl/community/merchants.md

_i18n/pl/community/sponsorships.md

_i18n/pl/community/team.md

_i18n/pl/downloads.md

_i18n/pl/get-started/accepting.md

_i18n/pl/get-started/contributing.md

_i18n/pl/get-started/faq.md

_i18n/pl/get-started/mining.md

_i18n/pl/get-started/using.md

_i18n/pl/get-started/what-is-monero.md

_i18n/pl/index.md