Docs: Update Microsoft and Apple documentation links for app icons in WP_Site_Icon.

Includes adding an up-to-date alternative for Chrome's “Add to Homescreen” link, previously  removed in r63568.

Follow-up to r33202, r32994, r63568.

Props dilip2615, mukesh27, SergeyBiryukov.
Fixes #66214.

git-svn-id: https://develop.svn.wordpress.org/trunk@64029 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/includes/class-wp-site-icon.php

@@ -41,21 +41,22 @@ class WP_Site_Icon {
 		/*
 		 * Square, medium sized tiles for IE11+.
 		 *
-		 * @link https://msdn.microsoft.com/library/dn455106(v=vs.85).aspx
+		 * @link https://learn.microsoft.com/en-us/previous-versions/windows/internet-explorer/ie-developer/samples/dn455106(v=vs.85)
 		 */
 		270,
 
 		/*
 		 * App icon for Android/Chrome.
 		 *
 		 * @link https://developer.chrome.com/blog/support-for-theme-color-in-chrome-39-for-android
+		 * @link https://web.dev/articles/icons-and-browser-colors
 		 */
 		192,
 
 		/*
 		 * App icons up to iPhone 6 Plus.
 		 *
-		 * @link https://developer.apple.com/library/prerelease/ios/documentation/UserExperience/Conceptual/MobileHIG/IconMatrix.html
+		 * @link https://developer.apple.com/design/human-interface-guidelines/app-icons
 		 */
 		180,