Small update of Colormap documentation

Small change in documentation: http://docs.opencv.org/master/d3/d50/group__imgproc__colormap.html#gga9a805d8262bcbe273f16be9ea2055a65a5d4a709cda1130bfa3cc4b4c5ae8f82a&gsc.tab=0

In the enum images, the "parula" colormap has wrongly assigned subtitle 'hot'

modules/imgproc/include/opencv2/imgproc.hpp

@@ -3768,7 +3768,7 @@ enum ColormapTypes
     COLORMAP_HSV = 9, //!< ![HSV](pics/colormaps/colorscale_hsv.jpg)
     COLORMAP_PINK = 10, //!< ![pink](pics/colormaps/colorscale_pink.jpg)
     COLORMAP_HOT = 11, //!< ![hot](pics/colormaps/colorscale_hot.jpg)
-    COLORMAP_PARULA = 12 //!< ![hot](pics/colormaps/colorscale_parula.jpg)
+    COLORMAP_PARULA = 12 //!< ![parula](pics/colormaps/colorscale_parula.jpg)
 };
 
 /** @brief Applies a GNU Octave/MATLAB equivalent colormap on a given image.