Librarian Bot: Add language metadata for dataset

Rename leipzig_enzw_web_2023_sentences_300k.csv to leipzig_enzw_web_2020_sentences_300k.csv

Rename leipzig_enzw_news_2023_sentences_300k.csv to leipzig_enzw_web_2023_sentences_300k.csv

Rename leipzig_enzw_news_2023_sentences_100k.csv to leipzig_enzw_news_2023_sentences_300k.csv

Rename leipzig_enzw_news_2023_sentences.csv to leipzig_enzw_news_2023_sentences_100k.csv

Upload leipzig_enzw_news_2023_sentences.csv

initial commit