Update README

README.md

@@ -1 +1,24 @@
-We will soon upload Spider, proposed in the paper "Learning to Retrieve Passages without Supervision".
+# Spider
+
+This is the unsupervised pretrained model discussed in our paper [Learning to Retrieve Passages without Supervision](https://arxiv.org/abs/2112.07708).
+
+## Usage
+
+We used weight sharing for the query encoder and passage encoder, so the same model should be applied for both.
+
+**Note**! We format the passages similar to DPR, i.e. the title and the text are separated by a `[SEP]` token, but token 
+type ids are all 0-s. 
+
+An example usage:
+
+```python
+from transformers import AutoTokenizer, DPRContextEncoder
+
+tokenizer = AutoTokenizer.from_pretrained("tau/spider")
+model = DPRContextEncoder.from_pretrained("tau/spider")
+
+input_dict = tokenizer("title", "text", return_tensors="pt")
+del input_dict["token_type_ids"]
+
+outputs = model(**input_dict)
+```