Corrected dimension notes in attention_wrapper.py (#12107)

tensorflow/contrib/seq2seq/python/ops/attention_wrapper.py

@@ -979,9 +979,9 @@ def _compute_attention(attention_mechanism, cell_output, previous_alignments,
   # alignments shape is
   #   [batch_size, 1, memory_time]
   # attention_mechanism.values shape is
-  #   [batch_size, memory_time, attention_mechanism.num_units]
+  #   [batch_size, memory_time, memory_size]
   # the batched matmul is over memory_time, so the output shape is
-  #   [batch_size, 1, attention_mechanism.num_units].
+  #   [batch_size, 1, memory_size].
   # we then squeeze out the singleton dim.
   context = math_ops.matmul(expanded_alignments, attention_mechanism.values)
   context = array_ops.squeeze(context, [1])