Added Rat Tumour Example (#3054)

* rat tumor example

Added notebook for rat tumor example in chapter 5 of BDA

* Made Edits

* Renamed notebook & Fixed Math

* More Edits

Author: Dpananos

docs/source/examples.rst

@@ -44,6 +44,7 @@ GLM
    notebooks/GLM-poisson-regression.ipynb
    notebooks/hierarchical_partial_pooling.ipynb
    notebooks/GLM-negative-binomial-regression.ipynb
+   notebooks/GLM-hierarchical-binominal-model.ipynb
 
 Gaussian Processes
 ==================
@@ -78,7 +79,7 @@ Variational Inference
    notebooks/convolutional_vae_keras_advi.ipynb
    notebooks/empirical-approx-overview.ipynb
    notebooks/normalizing_flows_overview.ipynb
-   
+
 
 Stochastic Gradient
 ===================