[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/lxmert.md

@@ -41,7 +41,9 @@ best result by 22% absolute (54% to 76%). Lastly, we demonstrate detailed ablati
 model components and pretraining strategies significantly contribute to our strong results; and also present several
 attention visualizations for the different encoders*
 
-Tips:
+This model was contributed by [eltoto1219](https://huggingface.co/eltoto1219). The original code can be found [here](https://github.com/airsplay/lxmert).
+
+## Usage tips
 
 - Bounding boxes are not necessary to be used in the visual feature embeddings, any kind of visual-spacial features
   will work.
@@ -53,9 +55,7 @@ Tips:
   contains self-attention for each respective modality and cross-attention, only the cross attention is returned and
   both self attention outputs are disregarded.
 
-This model was contributed by [eltoto1219](https://huggingface.co/eltoto1219). The original code can be found [here](https://github.com/airsplay/lxmert).
-
-## Documentation resources
+## Resources
 
 - [Question answering task guide](../tasks/question_answering)
 
@@ -83,6 +83,9 @@ This model was contributed by [eltoto1219](https://huggingface.co/eltoto1219). T
 
 [[autodoc]] models.lxmert.modeling_tf_lxmert.TFLxmertForPreTrainingOutput
 
+<frameworkcontent>
+<pt>
+
 ## LxmertModel
 
 [[autodoc]] LxmertModel
@@ -98,6 +101,9 @@ This model was contributed by [eltoto1219](https://huggingface.co/eltoto1219). T
 [[autodoc]] LxmertForQuestionAnswering
     - forward
 
+</pt>
+<tf>
+
 ## TFLxmertModel
 
 [[autodoc]] TFLxmertModel
@@ -107,3 +113,6 @@ This model was contributed by [eltoto1219](https://huggingface.co/eltoto1219). T
 
 [[autodoc]] TFLxmertForPreTraining
     - call
+
+</tf>
+</frameworkcontent>