Add more GitHub status values that can be ignored

Author: uhafner

.github/check-md-links.json

@@ -7,5 +7,5 @@
       }
     }
   ],
-  "aliveStatusCodes": [200, 500, 503, 429]
+  "aliveStatusCodes": [200, 500, 501, 502, 503, 429]
 }