[FOLLOW UP] : Documentation optimizations for the new Sphinx structure #29220
### Pull Request Readiness Checklist
This PR serves as a follow-up to the new documentation system introduced in [#29206](https://github.com/opencv/opencv/pull/29206)
Co-authored by: @abhishek-gola @kirtijindal14 @Akansha-977 @Prasadayus @varun-jaiswal17
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [x] The feature is well documented and sample code can be built with the project CMake
[GSoC] Develop OpenCV.js DNN modules for promising web use cases together with their tutorials
* [Opencv.js doc] Init commit to add image classification example in opencv.js tutorial
* [Opencv.js doc] Make the code snippet interactive and put the functions into code snippet.
* Fix the utils.loadOpenCv for promise module
* [Opencv.js doc] Code modify and fixed layout issue.
* [Opencv.js doc] Add a JSON file to store parameters for models and show in the web page.
* [Opencv.js doc] Change let to const.
* [Opencv.js doc] Init commit to add image classification example with camera in opencv.js tutorial
* [Opencv.js doc] Init commit to add semantic segmentation example in opencv.js tutorial
* [Opencv.js doc] Add object detection example, supprot YOLOv2
* [Opencv.js doc] Support SSD model for object detection example
* [Opencv.js doc] Add fast neural style transfer example with opencv.js
* [Opencv.js doc] Add pose estimation example in opencv.js tutorial
* Delete whitespace for code check
* [Opencv.js doc] Add object detection example with camera
* [Opencv.js doc] Add json files containing model information to each example
* [Opencv.js doc] Add a js file for common function in dnn example
* [Opencv.js doc] Create single function getBlobFromImage
* [Opencv.js doc] Add url of model into webpage
* [OpenCV.js doc] Update UI for running
* [Opencv.js doc] Load dnn model by input button
* [Opencv.js doc] Fix some UI issues
* [Opencv.js doc] Change code format
Co-authored-by: Ningxin Hu <ningxin.hu@intel.com>
omrope79
Alexander Alekhin
Zhiming-Zeng