update docstrings in BetaBinomial class

Author: saurbhc

pymc/distributions/discrete.py

@@ -244,11 +244,11 @@ def BetaBinom(a, b, n, x):
 
     Parameters
     ----------
-    n: int
+    n : tensor_like of int
         Number of Bernoulli trials (n >= 0).
-    alpha: float
+    alpha : tensor_like of float
         alpha > 0.
-    beta: float
+    beta : tensor_like of float
         beta > 0.
     """