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/"
     }
   ]
 }

CONTRIBUTING.md

@@ -176,7 +176,7 @@ language itself. Please note the following hints for your Ruby code:
 #### Comply with the Ruby standard (ISO/IEC 30170:2012)
 
 mruby is currently targeting to execute Ruby code which complies to ISO/IEC
-30170:2012 (<https://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=59579>),
+30170:2012 (<https://www.iso.org/standard/59579.html>),
 unless there's a clear reason, e.g. the latest Ruby has changed behavior from ISO.
 
 ## Building documentation

README.md

@@ -176,5 +176,5 @@ By contributing, you grant non-exclusive rights to your code under the MIT Licen
 
 [![mruby Contributors](https://contrib.rocks/image?repo=mruby/mruby&anon=1&max=500)](https://github.com/mruby/mruby/graphs/contributors)
 
-[ISO-standard]: https://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=59579
+[ISO-standard]: https://www.iso.org/standard/59579.html
 [contribution-guidelines]: CONTRIBUTING.md