Added URL that returns a 403 when tested from GitHub

docs/custom_conf.py

@@ -143,6 +143,7 @@
 # Links to ignore when checking links
 linkcheck_ignore = [
     'http://127.0.0.1:8000'
+    'https://leonelson.com/2011/08/15/how-to-increase-your-csr-key-size-on-microsoft-iis-without-removing-the-production-certificate/'
     ]
 
 # Pages on which to ignore anchors