update readme

Author: idoba2030

stan_modeling/models/confirmatory_two_alphas/README.md

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-## Model two alphas
-This is a model which has two separate alpha parameters depending on whether the prediction error was positive or negative. 
+## Model with confirmatory and disconfirmatory alphas
+This is a model which has two separate alpha parameters depending on whether the prediction error was positive or negative. It uses these alphas to update both chosen and unchosen cards. 
 
 Read ["The computational roots of positivity and
 confirmation biases in reinforcement learning"](https://www.sciencedirect.com/science/article/pii/S1364661322000894)