doc(palette.rs): Add document for a module

src/styles/palette.rs

@@ -1,13 +1,28 @@
+/// A module for creating palette color.
+///
+/// This module provides an struct `PaletteColor`
+/// that represents palette color, index should be between 0 to 255 mean u8.
+/// It also implements the `Stylify` trait for `PaletteColor`,
+/// which allows for generating styles based on the paint type.
+
+// =======================================================================
+
 use super::{ paint_type::PaintType, Stylify };
 
 // =======================================================================
 
+/// An struct representing index of palette color.
+///
+/// This struct has 1 field: `index`, which represent 8 bit color code between 0 to 255.
 #[derive(Debug, Clone)]
 pub struct PaletteColor {
     pub index: u8,
 }
 
 impl Stylify for PaletteColor {
+    /// Returns a string representation of the palette index code.
+    ///
+    /// If `paint_type` is `None`, the foreground color is assumed.
     fn make_styles(&self, paint_type: Option<&PaintType>) -> String {
         let paint_type = paint_type.unwrap_or(&PaintType::FG);
         format!(