[Docs] Model_doc structure/clarity improvements (#26876)

* first batch of structure improvements for model_docs

* second batch of structure improvements for model_docs

* more structure improvements for model_docs

* more structure improvements for model_docs

* structure improvements for cv model_docs

* more structural refactoring

* addressed feedback about image processors

docs/source/en/model_doc/encoder-decoder.md

@@ -149,20 +149,32 @@ were contributed by [ydshieh](https://github.com/ydshieh).
 
 [[autodoc]] EncoderDecoderConfig
 
+<frameworkcontent>
+<pt>
+
 ## EncoderDecoderModel
 
 [[autodoc]] EncoderDecoderModel
     - forward
     - from_encoder_decoder_pretrained
 
+</pt>
+<tf>
+
 ## TFEncoderDecoderModel
 
 [[autodoc]] TFEncoderDecoderModel
     - call
     - from_encoder_decoder_pretrained
 
+</tf>
+<jax>
+
 ## FlaxEncoderDecoderModel
 
 [[autodoc]] FlaxEncoderDecoderModel
     - __call__
     - from_encoder_decoder_pretrained
+
+</jax>
+</frameworkcontent>