Update Understanding SC 2.5.6 links (#4336)

- Fix link after redirect
- Fix Editor's Draft to stable document

Co-authored-by: Mike Gower 

Author: momdo

understanding/21/concurrent-input-mechanisms.html

@@ -46,10 +46,10 @@ Examples
 		<section id="resources">
 			<h2>Resourcesh2>
 			<ul>
-        <li><a href="https://w3c.github.io/pointerevents/">W3C Pointer Events - Level 2a>li>
+        <li><a href="https://www.w3.org/TR/pointerevents2/">W3C Pointer Events - Level 2a>li>
         <li><a href="https://hacks.mozilla.org/2013/04/detecting-touch-its-the-why-not-the-how/">Patrick H. Lauke - Detecting touch: it's the 'why', not the 'how'a>li>
-				<li><a href="https://www.html5rocks.com/en/mobile/touchandmouse/">Chris Wilson / Paul Kinlan: Touch And Mouse - Together Again For The First Time
-        </a>li><li><a href="https://w3c.github.io/touch-events/#mouse-events">W3C Touch Events - Level 2: Interaction with Mouse Events and clicka>li>
+				<li><a href="https://web.dev/articles/mobile-touchandmouse">Chris Wilson / Paul Kinlan: Touch And Mouse - Together Again For The First Timea>li>
+        <li><a href="https://www.w3.org/community/reports/touchevents/CG-FINAL-touch-events-20240704/#mouse-events">W3C Touch Events - Level 2: Interaction with Mouse Events and clicka>li>
         <li><a href="https://www.w3.org/TR/mediaqueries-4/#mf-interaction">W3C CSS Media Queries Level 4: Interaction Media Featuresa>li>
 			ul>
 		section>
@@ -59,7 +59,7 @@ Techniques
 				<h3>Sufficienth3>
 				<ul>
           <li>Only using high-level, input-agnostic event handlers, such as <code>focuscode>, <code>blurcode>, <code>clickcode>, in Javascript (Potential future technique).li>
-          <li> Registering event handlers for keyboard/keyboard-like and pointer inputs simultaneously in Javascript; see <a href="https://w3c.github.io/pointerevents/#examples">Example 1 in Pointer Events Level 2a> (Potential future technique)li>
+          <li>Registering event handlers for keyboard/keyboard-like and pointer inputs simultaneously in Javascript; see <a href="https://www.w3.org/TR/pointerevents2/#example_1">Example 1 in Pointer Events Level 2a> (Potential future technique)li>
         ul>
 			section>
 			<section id="failure">