Add lingua.py mention

README.md

@@ -77,9 +77,12 @@ made public by [SoftCatalà](https://github.com/Softcatala/Europarl-catalan).
 A last portion of the dataset is composed by synthetic parallel data generated from a random sampling of the Spanish-Portuguese corpora 
 available on [Opus](https://opus.nlpl.eu/) and translated into Catalan using the [PlanTL es-ca](https://huggingface.co/PlanTL-GOB-ES/mt-plantl-es-ca) model.
 
-All datasets are deduplicated and filtered to remove any sentence pairs with a cosine similarity of less than 0.75. 
-This is done using sentence embeddings calculated using [LaBSE](https://huggingface.co/sentence-transformers/LaBSE). 
-The filtered datasets are then concatenated to form the final corpus.
+All data was filtered according to two specific criteria:
+- Alignment: sentence level alignments were calculated using [LaBSE](https://huggingface.co/sentence-transformers/LaBSE) and sentence pairs with a score below 0.75 were discarded.
+
+- Language identification: the probability of being the target language was calculated using [Lingua.py](https://github.com/pemistahl/lingua-py) and sentences with a language probability score below 0.5 were discarded.
+
+The filtered datasets are then concatenated and deduplicated to form the final corpus.
 
 #### Who are the source language producers?