add module doc

mod.ts

@@ -1,6 +1,31 @@
 /**
  * A collection of functions to extract information from colors,
  * generate shades and tints, convert to other color spaces, etc.
+ *
+ * **Note: All methods either accept RGB/RGBA colors as parameters or give RGB/RGBA colors as results. In order to work with other color spaces (eg. XYZ), convert them to RGB first.**
+ *
+ * @example
+ * ```ts
+ * // Deno /x
+ * import { rgbaFromHex, xyz, lab } from "https://deno.land/x/colors/mod.ts";
+ *
+ * // Deno JSR
+ * import { rgbaFromHex, xyz, lab } from "jsr:@retraigo/colors";
+ *
+ * // Node JSR (after installation)
+ * import { rgbaFromHex, xyz, lab } from "jsr:@retraigo/colors";
+ *
+ * const color = rgbaFromHex("#fceff1");
+ *
+ * // CIE XYZ color space
+ * console.log(xyz(color));
+ *
+ * // CIE LAB color space
+ * console.log(lab(color));
+ *
+ * // Conversion of color into all supported spaces
+ * console.log(json(color));
+ * ```
  * @module
  */
 export * from "./src/mod.ts";