Change Keymap wording for gray image in curve mode
Change Keymap wording for gray image in curve mode

Instead of being a copy of line 76, line 79 instead correctly indicates that it will show a histogram for a gray image in curve mode, as given by the code block at line 103 referencing image "gray" instead of image "im".
opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv,opencv/opencv