[model_cards] Add a new model for Irish (#6544)

model_cards/jimregan/BERTreach/README.md

+---
+language: ga
+tags:
+- irish
+---
+
+## BERTreach
+
+([beirtreach](https://www.teanglann.ie/en/fgb/beirtreach) means 'oyster bed')
+
+**Model size:** 84M
+
+**Training data:** 
+* [PARSEME 1.2](https://gitlab.com/parseme/parseme_corpus_ga/-/blob/master/README.md) 
+* Newscrawl 300k portion of the [Leipzig Corpora](https://wortschatz.uni-leipzig.de/en/download/irish)
+* Private news corpus crawled with [Corpus Crawler](https://github.com/google/corpuscrawler)
+
+```
+from transformers import pipeline
+fill_mask = pipeline("fill-mask", model="jimregan/BERTreach", tokenizer="jimregan/BERTreach")
+```