Merge pull request #12657 from alalek:docs_repair_cuda_section

modules/core/include/opencv2/core/opengl.hpp

@@ -558,13 +558,11 @@ by the call to mapGLBuffer() function.
  */
 CV_EXPORTS void unmapGLBuffer(UMat& u);
 
+//! @}
 }} // namespace cv::ogl
 
 namespace cv { namespace cuda {
 
-//! @addtogroup cuda
-//! @{
-
 /** @brief Sets a CUDA device and initializes it for the current thread with OpenGL interoperability.
 
 This function should be explicitly called after OpenGL context creation and before any CUDA calls.
@@ -573,8 +571,6 @@ This function should be explicitly called after OpenGL context creation and befo
  */
 CV_EXPORTS void setGlDevice(int device = 0);
 
-//! @}
-
 }}
 
 //! @cond IGNORED