Bug #2960 : docs about CV_BGR2GRAY

modules/imgproc/doc/miscellaneous_transformations.rst

@@ -116,6 +116,7 @@ If you use ``cvtColor`` with 8-bit images, the conversion will have some informa
 The function can do the following transformations:
 
 *
+    RGB :math:`\leftrightarrow` GRAY ( ``CV_BGR2GRAY, CV_RGB2GRAY, CV_GRAY2BGR, CV_GRAY2RGB``     )
     Transformations within RGB space like adding/removing the alpha channel, reversing the channel order, conversion to/from 16-bit RGB color (R5:G6:B5 or R5:G5:B5), as well as conversion to/from grayscale using:
 
     .. math::