core: improve doc for setNumThreads

The old documentation implies that the call is only valid for the next parallel region and must be called again if addtional regions should be affected as well.

modules/core/include/opencv2/core/utility.hpp

@@ -179,7 +179,7 @@ CV_EXPORTS ErrorCallback redirectError( ErrorCallback errCallback, void* userdat
 CV_EXPORTS String tempfile( const char* suffix = 0);
 CV_EXPORTS void glob(String pattern, std::vector<String>& result, bool recursive = false);
 
-/** @brief OpenCV will try to set the number of threads for the next parallel region.
+/** @brief OpenCV will try to set the number of threads for subsequent parallel regions.
 
 If threads == 0, OpenCV will disable threading optimizations and run all it's functions
 sequentially. Passing threads \< 0 will reset threads number to system default. This function must