Update __init__.py

Author: LeonShams

tensorflow_addons/layers/__init__.py

@@ -38,3 +38,4 @@
 from tensorflow_addons.layers.tlu import TLU
 from tensorflow_addons.layers.wrappers import WeightNormalization
 from tensorflow_addons.layers.esn import ESN
+from tensorflow_addons.layers.noisy_dense import NoisyDense