[BUGFIX] [DOC] Update nlp.model.get_model documentation and get_model…

… API (#734)

* Improve gluonnlp.model docs

* Fix nlp.model.get_model API

* Update model.rst

docs/api/modules/model.rst

@@ -6,24 +6,45 @@ all requested pre-trained weights are downloaded from public repo and stored in
 
 .. currentmodule:: gluonnlp.model
 
+Model Registry
+--------------
+
+The model registry provides an easy interface to obtain pre-defined and pre-trained models.
+
+.. autosummary::
+    :nosignatures:
+
+    get_model
+
+The `get_model` function returns a pre-defined model given the name of a
+registered model. The following sections of this page present a list of
+registered names for each model category.
+
 Language Modeling
 -----------------
 
+Components
+
 .. autosummary::
     :nosignatures:
 
-    awd_lstm_lm_1150
-    awd_lstm_lm_600
     AWDRNN
     BiLMEncoder
     LSTMPCellWithClip
+    StandardRNN
+    BigRNN
+
+Pre-defined models
+
+.. autosummary::
+    :nosignatures:
+
+    awd_lstm_lm_1150
+    awd_lstm_lm_600
     standard_lstm_lm_200
     standard_lstm_lm_650
     standard_lstm_lm_1500
     big_rnn_lm_2048_512
-    StandardRNN
-    get_model
-    BigRNN
 
 Machine Translation
 -------------------
@@ -35,11 +56,17 @@ Machine Translation
     TransformerEncoder
     TransformerEncoderCell
     PositionwiseFFN
+
+.. autosummary::
+    :nosignatures:
+
     transformer_en_de_512
 
 Bidirectional Encoder Representations from Transformers
 -------------------------------------------------------
 
+Components
+
 .. autosummary::
     :nosignatures:
 
@@ -48,26 +75,43 @@ Bidirectional Encoder Representations from Transformers
     BERTEncoder
     BERTEncoderCell
     BERTPositionwiseFFN
+
+Pre-defined models
+
+.. autosummary::
+    :nosignatures:
+
     bert_12_768_12
     bert_24_1024_16
 
 Convolutional Encoder
-----------------------
+---------------------
 
 .. autosummary::
     :nosignatures:
 
     ConvolutionalEncoder
 
 ELMo
-----------------------
+----
+
+Components
 
 .. autosummary::
     :nosignatures:
 
     ELMoBiLM
     ELMoCharacterEncoder
 
+Pre-defined models
+
+.. autosummary::
+    :nosignatures:
+
+    elmo_2x1024_128_2048cnn_1xhighway
+    elmo_2x2048_256_2048cnn_1xhighway
+    elmo_2x4096_512_2048cnn_2xhighway
+
 Highway Network
 -----------------
 

src/gluonnlp/model/__init__.py

@@ -96,14 +96,14 @@
           seq2seq_encoder_decoder.__all__ + transformer.__all__ + bert.__all__
 
 
-def get_model(name, dataset_name='wikitext-2', **kwargs):
+def get_model(name, **kwargs):
     """Returns a pre-defined model by name.
 
     Parameters
     ----------
     name : str
         Name of the model.
-    dataset_name : str or None, default 'wikitext-2'.
+    dataset_name : str or None, default None
         The dataset name on which the pre-trained model is trained.
         For language model, options are 'wikitext-2'.
         For ELMo, Options are 'gbw' and '5bw'.
@@ -147,5 +147,4 @@ def get_model(name, dataset_name='wikitext-2', **kwargs):
         raise ValueError(
             'Model %s is not supported. Available options are\n\t%s'%(
                 name, '\n\t'.join(sorted(models.keys()))))
-    kwargs['dataset_name'] = dataset_name
     return models[name](**kwargs)