Add factor_signals.parquet and README.md

README.md

@@ -13,7 +13,7 @@ description: >-
 
 ```python
 from datasets import load_dataset
-df_factor_comp = load_dataset("sovai/factor_signals", split="train").to_pandas().set_index(["factor","date"])
+df_factor_comp = load_dataset("sovai/factor_signals", split="train").to_pandas().set_index(["ticker","date"])
 ```