Change the v4l2-chroma long help string.

modules/access/v4l2.c

@@ -81,7 +81,9 @@ static void Close( vlc_object_t * );
 #define CHROMA_TEXT N_("Video input chroma format")
 #define CHROMA_LONGTEXT N_( \
     "Force the Video4Linux2 video device to use a specific chroma format " \
-    "(eg. I420, RV24, etc.)")
+    "(eg. I420 or I422 for raw images, MJPEG for M-JPEG compressed input) " \
+    "(Complete list: GREY, I240, RV16, RV15, RV24, RV32, YUY2, YUYV, UYVY, " \
+    "I41N, I422, I420, I411, I410, MJPG)")
 #define INPUT_TEXT N_( "Input" )
 #define INPUT_LONGTEXT N_( \
     "Input of the card to use (Usually, 0 = tuner, " \