linking white paper and lower case irt model selection

app/lib/irt/models/rasch.py

@@ -5,6 +5,9 @@ from lib.irt.models.base import *
 class Rasch(Base):
 
   def result(self):
+    # contains the primary Rasch function, determining the probably of an inidividual
+    # that an individual at a certain theta would get a particular question correct
+    # https://edres.org/irt/baker/chapter6.pdf
     return (1 / (1 + self.e(-1 * (self.theta - self.b_param))))
 
   @classmethod