Add a rule for markdownlint to allow multiple headers with the same name as long

as they are not nested in the same heading group.

.mdl_config.json

@@ -3,5 +3,8 @@
     "code_blocks": false,
     "tables": false
   },
+  "MD024": {
+    "allow_different_nesting": true
+  },
   "default": true
 }