modify plot_functions' descriptions to make them clearer

sohstationviewer/view/util/plot_func_names.py

 plot_functions = {
         'linesDots': (
-            "Lines, one color dots. ",
+            "Lines, one color dots. Dot or line/color mapping defined by "
+            "ValueColors with available colors: RYGMCW.\n"
+            "Ex: L:G|D:W\n"
+            "  means Lines are plotted with color G\n"
+            "        Dots are plotted with color W\n"
+            "If D is not defined, dots won't be displayed.\n"
+            "If L is not defined, lines will be plotted with color G",
             "plot_lines_dots"),
         'linesSRate': (
             "Lines, one color dots, bitweight info. ",
@@ -12,18 +18,23 @@ plot_functions = {
         #     ("mass position, multi-color, single line. "),
         #     "plotDotsMasspos"),
         'dotForTime': (
-            "Dots according to timestamp. Color defined by valueColors. Ex: G",
+            "Dots according to timestamp."
+            "Color defined by ValueColors with available colors: RYGMCW.\n"
+            "Ex: G",
             "plot_time_dots"),
         'multiColorDots': (
-            ("Multicolor dots with colors defined by valueColors. "
-             "Value from low to high. "
-             "Ex:*:W or -1:_|0:R|2.3:Y|+2.3:G. "
-             "With colors: RYGMC: _: not plot"),
+            ("Multicolor dots with value/colors mapping defined by "
+             "ValueColors with available colors: RYGMCW.\n"
+             "Value from low to high.\n"
+             "Ex: *:W\n"
+             "  means all values represent by white dots."
+             "Ex: -1:_|0:R|2.3:Y|+2.3:G\n"
+             "  in which '-1:_' means no plotting for value <-1"),
             "plot_multi_color_dots"
         ),
         'upDownDots': (
             ("Show data with 2 different values: first down/ second up. "
-             "With colors defined by valueColors. Ex: 1:R|0:Y"),
+             "With colors defined by ValueColors.\nEx: 1:R|0:Y"),
             'plot_up_down_dots'
         )
     }