[docstring] missing arg (#6933)

* [docstring] missing arg

add the missing `tie_word_embeddings` entry

* cleanup

* Update src/transformers/configuration_reformer.py
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>

src/transformers/configuration_reformer.py

@@ -115,6 +115,8 @@ class ReformerConfig(PretrainedConfig):
         vocab_size (:obj:`int`, optional, defaults to 320):
             Vocabulary size of the Reformer model. Defines the different tokens that
             can be represented by the `inputs_ids` passed to the forward method of :class:`~transformers.ReformerModel`.
+        tie_word_embeddings (:obj:`bool`, `optional`, defaults to :obj:`False`):
+            Whether to tie input and output embeddings.
 
     Example::