[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/bert.md

@@ -45,7 +45,9 @@ language processing tasks, including pushing the GLUE score to 80.5% (7.7% point
 accuracy to 86.7% (4.6% absolute improvement), SQuAD v1.1 question answering Test F1 to 93.2 (1.5 point absolute
 improvement) and SQuAD v2.0 Test F1 to 83.1 (5.1 point absolute improvement).*
 
-Tips:
+This model was contributed by [thomwolf](https://huggingface.co/thomwolf). The original code can be found [here](https://github.com/google-research/bert).
+
+## Usage tips
 
 - BERT is a model with absolute position embeddings so it's usually advised to pad the inputs on the right rather than
   the left.
@@ -59,10 +61,6 @@ Tips:
     
 - The model must predict the original sentence, but has a second objective: inputs are two sentences A and B (with a separation token in between). With probability 50%, the sentences are consecutive in the corpus, in the remaining 50% they are not related. The model has to predict if the sentences are consecutive or not.
 
-
-
-This model was contributed by [thomwolf](https://huggingface.co/thomwolf). The original code can be found [here](https://github.com/google-research/bert).
-
 ## Resources
 
 A list of official Hugging Face and community (indicated by 🌎) resources to help you get started with BERT. If you're interested in submitting a resource to be included here, please feel free to open a Pull Request and we'll review it! The resource should ideally demonstrate something new instead of duplicating an existing resource.
@@ -137,14 +135,23 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
     - create_token_type_ids_from_sequences
     - save_vocabulary
 
+<frameworkcontent>
+<pt>
+
 ## BertTokenizerFast
 
 [[autodoc]] BertTokenizerFast
 
+</pt>
+<tf>
+
 ## TFBertTokenizer
 
 [[autodoc]] TFBertTokenizer
 
+</tf>
+</frameworkcontent>
+
 ## Bert specific outputs
 
 [[autodoc]] models.bert.modeling_bert.BertForPreTrainingOutput
@@ -153,6 +160,10 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 
 [[autodoc]] models.bert.modeling_flax_bert.FlaxBertForPreTrainingOutput
 
+
+<frameworkcontent>
+<pt>
+
 ## BertModel
 
 [[autodoc]] BertModel
@@ -198,6 +209,9 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 [[autodoc]] BertForQuestionAnswering
     - forward
 
+</pt>
+<tf>
+
 ## TFBertModel
 
 [[autodoc]] TFBertModel
@@ -243,6 +257,9 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 [[autodoc]] TFBertForQuestionAnswering
     - call
 
+</tf>
+<jax>
+
 ## FlaxBertModel
 
 [[autodoc]] FlaxBertModel
@@ -287,3 +304,8 @@ A list of official Hugging Face and community (indicated by 🌎) resources to h
 
 [[autodoc]] FlaxBertForQuestionAnswering
     - __call__
+
+</jax>
+</frameworkcontent>
+
+