[bgsegm] Fix typo: impemented -> implemented

Author: kashish2710

modules/bgsegm/include/opencv2/bgsegm.hpp

@@ -147,7 +147,7 @@ class CV_EXPORTS_W BackgroundSubtractorGMG : public BackgroundSubtractor
     rate. 0 means that the background model is not updated at all, 1 means that the background model
     is completely reinitialized from the last frame.
 
-    @note This method has a default virtual implementation that throws a "not impemented" error.
+    @note This method has a default virtual implementation that throws a "not implemented" error.
     Foreground masking may not be supported by all background subtractors.
     */
     CV_WRAP virtual void apply(InputArray image, InputArray knownForegroundMask, OutputArray fgmask, double learningRate=-1) CV_OVERRIDE = 0;