[Doctest] Add configuration_dpr.py (#20080)

* Add example docstring for DPRConfig

* Add DPRConfig to documentation_tests

src/transformers/models/dpr/configuration_dpr.py

@@ -92,7 +92,21 @@ class DPRConfig(PretrainedConfig):
         projection_dim (`int`, *optional*, defaults to 0):
             Dimension of the projection for the context and question encoders. If it is set to zero (default), then no
             projection is done.
-    """
+
+    Example:
+
+    ```python
+    >>> from transformers import DPRConfig, DPRContextEncoder
+
+    >>> # Initializing a DPR facebook/dpr-ctx_encoder-single-nq-base style configuration
+    >>> configuration = DPRConfig()
+
+    >>> # Initializing a model (with random weights) from the facebook/dpr-ctx_encoder-single-nq-base style configuration
+    >>> model = DPRContextEncoder(configuration)
+
+    >>> # Accessing the model configuration
+    >>> configuration = model.config
+    ```"""
     model_type = "dpr"
 
     def __init__(

utils/documentation_tests.txt

@@ -62,6 +62,7 @@ src/transformers/models/deit/modeling_tf_deit.py
 src/transformers/models/detr/configuration_detr.py
 src/transformers/models/detr/modeling_detr.py
 src/transformers/models/distilbert/configuration_distilbert.py
+src/transformers/models/dpr/configuration_dpr.py
 src/transformers/models/dpt/modeling_dpt.py
 src/transformers/models/electra/configuration_electra.py
 src/transformers/models/electra/modeling_electra.py