Replace the recommended lazyloading library

lib/metadata/policies.js

@@ -869,7 +869,7 @@ var policies = {
     "lazyLoadableImagesBelowTheFold": {
         "tool": "phantomas",
         "label": "Below the fold images",
-        "message": "<p>This is the number of images displayed below the fold that could be lazy-loaded. This is an excellent way to accelerate the loading time of an heavy page.</p><p>I recommend using <a href=\"https://github.com/vvo/lazyload\" target=\"_blank\">this lazyloader</a>.</p>",
+        "message": "<p>This is the number of images displayed below the fold that could be lazy-loaded. This is an excellent way to accelerate the loading time of an heavy page.</p><p>I recommend using <a href=\"https://github.com/aFarkas/lazysizes\" target=\"_blank\">lazysizes</a> or <a href=\"https://github.com/ApoorvSaxena/lozad.js\" target=\"_blank\">Lozad</a>.</p>",
         "isOkThreshold": 1,
         "isBadThreshold": 12,
         "isAbnormalThreshold": 30,