mlc_config.json: ignore iso.org links in markdown-link-check

iso.org blocks automated HTTP requests with 403 Forbidden.
Also update the ISO 30170 URLs to current format in README.md
and CONTRIBUTING.md.

Co-authored-by: Claude <noreply@anthropic.com>

.github/linters/mlc_config.json

@@ -11,6 +11,9 @@
     },
     {
       "pattern": "^mailto:"
+    },
+    {
+      "pattern": "^https://www.iso.org/"
     }
   ]
 }