Merge pull request #26441 from sturkmen72:upd_tutorials

Update tutorials #26441

### Pull Request Readiness Checklist

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- [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
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake

doc/tutorials/core/mat_the_basic_image_container/mat_the_basic_image_container.markdown

@@ -148,7 +148,7 @@ picture in memory.
 Creating a Mat object explicitly
 ----------------------------------
 
-In the @ref tutorial_load_save_image tutorial you have already learned how to write a matrix to an image
+In the @ref tutorial_display_image tutorial you have already learned how to write a matrix to an image
 file by using the @ref cv::imwrite() function. However, for debugging purposes it's much more
 convenient to see the actual values. You can do this using the \<\< operator of *Mat*. Be aware that
 this only works for two dimensional matrices.

doc/tutorials/core/table_of_content_core.markdown

@@ -1,12 +1,17 @@
 The Core Functionality (core module) {#tutorial_table_of_content_core}
 =====================================
 
+@tableofcontents
+
+##### Basic
 -   @subpage tutorial_mat_the_basic_image_container
 -   @subpage tutorial_how_to_scan_images
 -   @subpage tutorial_mat_mask_operations
 -   @subpage tutorial_mat_operations
 -   @subpage tutorial_adding_images
 -   @subpage tutorial_basic_linear_transform
+
+##### Advanced
 -   @subpage tutorial_discrete_fourier_transform
 -   @subpage tutorial_file_input_output_with_xml_yml
 -   @subpage tutorial_how_to_use_OpenCV_parallel_for_new