added external links to tutorials

README.md

@@ -61,7 +61,11 @@ widget:
 # astroBERT base model 
 Pretrained model on English language using a masked language modeling (MLM) and next sentence prediction (NSP) objective.  
 It was introduced in [this paper at ADASS 2021](https://arxiv.org/abs/2112.00590).  
-This model is cased. 
+This model is cased (it treats `ads` and `ADS` differently). 
+
+## Tutorials
+0. [Embeddings](https://nbviewer.org/urls/huggingface.co/adsabs/astroBERT/raw/main/Tutorials/0_Embeddings.ipynb)
+1. [Fill-Mask](https://nbviewer.org/urls/huggingface.co/adsabs/astroBERT/raw/main/Tutorials/1_Fill-Mask.ipynb)
 
 
 ### BibTeX