Improve config documentation

update readme to provide some direction on customization options.

readme.md

@@ -96,7 +96,25 @@ yay -S ly
 
 ## Configuration
 You can find all the configuration in `/etc/ly/config.ini`.
-The file is commented, and includes the default values.
+The file is commented, and includes the default values. The `fg` and `bg` color settings take a digit 0-8 corresponding to
+```
+#define TB_DEFAULT 0x00
+#define TB_BLACK   0x01
+#define TB_RED     0x02
+#define TB_GREEN   0x03
+#define TB_YELLOW  0x04
+#define TB_BLUE    0x05
+#define TB_MAGENTA 0x06
+#define TB_CYAN    0x07
+#define TB_WHITE   0x08
+```
+Setting both to zero makes `bg` black and `fg` white. To set the actual color palette you are encouraged to use another tool 
+such as [mkinitcpio-colors](https://github.com/evanpurkhiser/mkinitcpio-colors). Note that the color palette defined with 
+`mkinitcpio-colors` takes 16 colors (0-15), only values 0-8 are valid for `ly` config and these values do not correspond 
+exactly. For instance, in defining palettes with `mkinitcpio-colors` the order is black, dark red, dark green, brown, dark 
+blue, dark purple, dark cyan, light gray, dark gray, bright red, bright green, yellow, bright blue, bright purple, bright 
+cyan, and white, indexed in that order 0 through 15. For example, the color defined for white (indexed at 15 in the mkinitcpio 
+config)will be used by `ly` for `fg = 8`.
 
 ## Controls
 Use the up and down arrow keys to change the current field, and the