Fix key name to switch between MSER/CSER regions.

modules/text/samples/webcam_demo.cpp

@@ -87,7 +87,7 @@ int main(int argc, char* argv[])
     cout << endl << argv[0] << endl << endl;
     cout << "A demo program of End-to-end Scene Text Detection and Recognition using webcam." << endl << endl;
     cout << "  Usage:  " << argv[0] << " [camera_index]" << endl << endl;
-    cout << "  Press 'e' to switch between MSER/CSER regions." << endl;
+    cout << "  Press 'r' to switch between MSER/CSER regions." << endl;
     cout << "  Press 'g' to switch between Horizontal and Arbitrary oriented grouping." << endl;
     cout << "  Press 'o' to switch between OCRTesseract/OCRHMMDecoder recognition." << endl;
     cout << "  Press 's' to scale down frame size to 320x240." << endl;