[model_cards] Add language metadata to existing model cards

This will enable filtering on language (amongst other tags) on the website

cc @loretoparisi, @stefan-it, @HenrykBorzymowski, @marma

model_cards/KB/albert-base-swedish-cased-alpha/README.md

+---
+language: swedish
+---
+
 # Swedish BERT Models
 
 The National Library of Sweden / KBLab releases three pretrained language models based on BERT and ALBERT. The models are trained on aproximately 15-20GB of text (200M sentences, 3000M tokens) from various sources (books, news, government publications, swedish wikipedia and internet forums) aiming to provide a representative BERT model for Swedish text. A more complete description will be published later on.

model_cards/KB/bert-base-swedish-cased-ner/README.md

+---
+language: swedish
+---
+
 # Swedish BERT Models
 
 The National Library of Sweden / KBLab releases three pretrained language models based on BERT and ALBERT. The models are trained on aproximately 15-20GB of text (200M sentences, 3000M tokens) from various sources (books, news, government publications, swedish wikipedia and internet forums) aiming to provide a representative BERT model for Swedish text. A more complete description will be published later on.

model_cards/KB/bert-base-swedish-cased/README.md

+---
+language: swedish
+---
+
 # Swedish BERT Models
 
 The National Library of Sweden / KBLab releases three pretrained language models based on BERT and ALBERT. The models are trained on aproximately 15-20GB of text (200M sentences, 3000M tokens) from various sources (books, news, government publications, swedish wikipedia and internet forums) aiming to provide a representative BERT model for Swedish text. A more complete description will be published later on.

model_cards/Musixmatch/umberto-commoncrawl-cased-v1/README.md

+---
+language: italian
+---
+
 # UmBERTo Commoncrawl Cased
 
 [UmBERTo](https://github.com/musixmatchresearch/umberto) is a Roberta-based Language Model trained on large Italian Corpora and uses two innovative approaches: SentencePiece and Whole Word Masking. Now available at [github.com/huggingface/transformers](https://huggingface.co/Musixmatch/umberto-commoncrawl-cased-v1)

model_cards/Musixmatch/umberto-wikipedia-uncased-v1/README.md

+---
+language: italian
+---
+
 # UmBERTo Wikipedia Uncased
 
 [UmBERTo](https://github.com/musixmatchresearch/umberto) is a Roberta-based Language Model trained on large Italian Corpora and uses two innovative approaches: SentencePiece and Whole Word Masking. Now available at [github.com/huggingface/transformers](https://huggingface.co/Musixmatch/umberto-commoncrawl-cased-v1)

model_cards/canwenxu/BERT-of-Theseus-MNLI/README.md

 ---
-thumbnail: https://github.com/JetRunner/BERT-of-Theseus/blob/master/bert-of-theseus.png?raw=true
+thumbnail: https://raw.githubusercontent.com/JetRunner/BERT-of-Theseus/master/bert-of-theseus.png
 ---
 
 # BERT-of-Theseus

model_cards/dbmdz/bert-base-german-cased/README.md

+---
+language: german
+---
+
 # 🤗 + 📚 dbmdz German BERT models
 
 In this repository the MDZ Digital Library team (dbmdz) at the Bavarian State

model_cards/dbmdz/bert-base-german-uncased/README.md

+---
+language: german
+---
+
 # 🤗 + 📚 dbmdz German BERT models
 
 In this repository the MDZ Digital Library team (dbmdz) at the Bavarian State

model_cards/dbmdz/bert-base-italian-cased/README.md

+---
+language: italian
+---
+
 # 🤗 + 📚 dbmdz BERT models
 
 In this repository the MDZ Digital Library team (dbmdz) at the Bavarian State

model_cards/dbmdz/bert-base-italian-uncased/README.md

+---
+language: italian
+---
+
 # 🤗 + 📚 dbmdz BERT models
 
 In this repository the MDZ Digital Library team (dbmdz) at the Bavarian State

model_cards/dbmdz/bert-base-italian-xxl-cased/README.md

+---
+language: italian
+---
+
 # 🤗 + 📚 dbmdz BERT models
 
 In this repository the MDZ Digital Library team (dbmdz) at the Bavarian State

model_cards/dbmdz/bert-base-italian-xxl-uncased/README.md

+---
+language: italian
+---
+
 # 🤗 + 📚 dbmdz BERT models
 
 In this repository the MDZ Digital Library team (dbmdz) at the Bavarian State

model_cards/henryk/bert-base-multilingual-cased-finetuned-dutch-squad2/README.md

+---
+language: dutch
+---
+
 # Multilingual + Dutch SQuAD2.0
 
 This model is the multilingual model provided by the Google research team with a fine-tuned dutch Q&A downstream task.