Rename <>_posterior_predictive to <>_predictive (#95)

* migrate from posterior_predictive to predictive

* deprecate the previous function names

* add missing comments section

* test for the deprecation

README.md

@@ -43,18 +43,18 @@ Many likelihoods are supported including
 
 ```python 
 from conjugate.distributions import Beta, BetaBinomial
-from conjugate.models import binomial_beta, binomial_beta_posterior_predictive
+from conjugate.models import binomial_beta, binomial_beta_predictive
 
 # Observed Data
 X = 4
 N = 10
 
 # Analytics
 prior = Beta(1, 1)
-prior_predictive: BetaBinomial = binomial_beta_posterior_predictive(n=N, beta=prior)
+prior_predictive: BetaBinomial = binomial_beta_predictive(n=N, beta=prior)
 
 posterior: Beta = binomial_beta(n=N, x=X, beta_prior=prior)
-posterior_predictive: BetaBinomial = binomial_beta_posterior_predictive(n=N, beta=posterior) 
+posterior_predictive: BetaBinomial = binomial_beta_predictive(n=N, beta=posterior) 
 ```
 
 From here, do any analysis you'd like!