Add a colab to explain how to use scaffold classes to build noval achitectures.

PiperOrigin-RevId: 320149378

official/nlp/modeling/README.md

@@ -17,7 +17,8 @@ standardized configuration.
 * [`losses`](losses) contains common loss computation used in NLP tasks.
 
 Please see the colab
-[Introduction_to_NLP_Modeling_Library.ipynb](https://colab.sandbox.google.com/github/tensorflow/models/blob/master/official/colab/nlp/nlp_modeling_library_intro.ipynb)
+[nlp_modeling_library_intro.ipynb]
+(https://colab.sandbox.google.com/github/tensorflow/models/blob/master/official/colab/nlp/nlp_modeling_library_intro.ipynb)
 for how to build transformer-based NLP models using above primitives.
 
 Besides the pre-defined primitives, it also provides scaffold classes to allow
@@ -37,11 +38,9 @@ embedding subnetwork (which will replace the standard embedding logic) and/or a
 custom hidden layer (which will replace the Transformer instantiation in the
 encoder).
 
-BERT and ALBERT models in this repo are implemented using this library. Code examples can be found in the corresponding model folder.
-
-
-
-
-
-
+Please see the colab
+[customize_encoder.ipynb]
+(https://colab.sandbox.google.com/github/tensorflow/models/blob/master/official/colab/nlp/customize_encoder.ipynb)
+for how to use scaffold classes to build noval achitectures.
 
+BERT and ALBERT models in this repo are implemented using this library. Code examples can be found in the corresponding model folder.