Fixes documantion for back Easing

Summary:
The documentation of back easing contains a old link that
is now stale. I'm updating it to link to https://easings.net/#easeInBack

Fixes #32419

Changelog:
[Android] [Fixed] - Fixes documentation for back Easing animation

Reviewed By: hramos

Differential Revision: D31728560

fbshipit-source-id: 99f7aa60d3748af5429b4ae1aa6cbd79326c5fe6

Libraries/Animated/Easing.js

@@ -171,9 +171,7 @@ class Easing {
    * Use with `Animated.parallel()` to create a simple effect where the object
    * animates back slightly as the animation starts.
    *
-   * Wolfram Plot:
-   *
-   * - http://tiny.cc/back_default (s = 1.70158, default)
+   * https://easings.net/#easeInBack
    */
   static back(s: number = 1.70158): (t: number) => number {
     return t => t * t * ((s + 1) * t - s);