Provide exact link for the origin of the library

As per AMO review team request.

Related documentation:
- https://extensionworkshop.com/documentation/publish/third-party-library-usage/

src/lib/hsluv/README

@@ -0,0 +1,3 @@
+Source:
+
+https://github.com/hsluv/hsluv/blob/9cd8574fad8874828b3a8119843527d62d79887a/javascript/dist/hsluv-0.1.0.min.js

src/lib/hsluv/README.md

@@ -1,78 +0,0 @@
-# HSLuv - Human-friendly HSL
-
-## Installation
-
-Client-side: download [the latest hsluv.min.js](https://github.com/hsluv/hsluv/tree/master/javascript/dist).
-
-Once this module is loaded in the browser, you can access it via the
-global ``window.hsluv``.
-
-Server-side: ``npm install hsluv``.
-
-## Usage
-
-Most functions take tuples, ie: Javascript arrays with three elements.  Make sure you are using
-`func([a,b,c])` and not `func(a,b,c)`. If you are getting NaN for output then this is probably
-the problem.
-
-**hsluvToHex([hue, saturation, lightness])**
-
-*hue* is a number between 0 and 360, *saturation* and *lightness* are
-numbers between 0 and 100. This function returns the resulting color as
-a hex string.
-
-**hsluvToRgb([hue, saturation, lightness])**
-
-Like above, but returns an array of 3 numbers between 0 and 1, for the
-r, g, and b channel.
-
-**hexToHsluv(hex)**
-
-Takes a hex string and returns the HSLuv color as array that contains
-the hue (0-360), saturation (0-100) and lightness (0-100) channel.
-_Note:_ The result can have rounding errors. For example saturation can
-be 100.00000000000007
-
-**rgbToHsluv([red, green, blue])**
-
-Like above, but *red*, *green* and *blue* are passed as numbers between
-0 and 1.
-
-Use **hpluvToHex**, **hpluvToRgb**, **hexToHpluv** and **rgbToHpluv** for
-the pastel variant (HPLuv). Note that HPLuv does not contain all the colors
-of RGB, so converting arbitrary RGB to it may generate invalid HPLuv colors.
-
-For advance use cases, additional functions are avalible:
-
-**hsluvToLch**, **lchToHsluv**
-
-**hpluvToLch**, **lchToHpluv**
-
-**rgbToXyz**, **xyzToRgb**
-
-**rgbToLch**, **lchToRgb**
-
-**luvToXyz**, **xyzToLuv**
-
-**lchToLuv**, **luvToLch**
-
-Also available for [Stylus](http://stylus-lang.com/). See
-[here](https://github.com/hsluv/hsluv-stylus).
-
-## Changelog
-
-### 0.1.0
-
-- Provide Typescript definitions in the NPM package.
-
-### 0.0.3
-
-- Expose intermediate functions in the public API.
-
-### 0.0.2
-
-- Improve packaging and minification.
-
-### 0.0.1
-
-- Initial release under the name HSLuv. Old releases can be found [here](https://www.npmjs.com/package/husl).