Merge pull request #27039 from chacha21:threshold_otsu_doc_update

Threshold otsu doc update #27039 
 
PR for #27038

(I had already done that, but encounters git madness after branch renaming)

- [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

modules/imgproc/include/opencv2/imgproc.hpp

@@ -3070,9 +3070,10 @@ Also, the special values #THRESH_OTSU or #THRESH_TRIANGLE may be combined with o
 above values. In these cases, the function determines the optimal threshold value using the Otsu's
 or Triangle algorithm and uses it instead of the specified thresh.
 
-@note Currently, the Otsu's and Triangle methods are implemented only for 8-bit single-channel images.
+@note Currently, the Otsu's method is implemented only for CV_8UC1 and CV_16UC1 images,
+and the Triangle's method is implemented only for CV_8UC1 images.
 
-@param src input array (multiple-channel, 8-bit or 32-bit floating point).
+@param src input array (multiple-channel, CV_8U, CV_16S, CV_16U, CV_32F or CV_64F).
 @param dst output array of the same size  and type and the same number of channels as src.
 @param thresh threshold value.
 @param maxval maximum value to use with the #THRESH_BINARY and #THRESH_BINARY_INV thresholding