Fix Layer class name in docstring (#2118)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: bot-of-gabrieldemarmiesse

tensorflow_addons/seq2seq/attention_wrapper.py

@@ -1664,8 +1664,8 @@ def __init__(
             `get_initial_state` which does not match the batch size of
             `initial_cell_state`, proper behavior is not guaranteed.
           name: Name to use when creating ops.
-          attention_layer: A list of `tf.tf.keras.layers.Layer` instances or a
-            single `tf.tf.keras.layers.Layer` instance taking the context
+          attention_layer: A list of `tf.keras.layers.Layer` instances or a
+            single `tf.keras.layers.Layer` instance taking the context
             and cell output as inputs to generate attention at each time step.
             If None (default), use the context as attention at each time step.
             If attention_mechanism is a list, attention_layer must be a list of