fix(lint): re-arrange scripts (#36511)

tools/scripts/lint/.markdownlintrc.js

@@ -0,0 +1,11 @@
+// JS rather than JSON so comments can be included
+
+module.exports = {
+  "default": true,  // include all rules, with exceptions below
+  "MD002": false,   // first heading should not be a top level heading
+  "MD013": false,   // lines can be any length
+  "MD022": false,   // headings don't need surrounding by newlines
+  "MD031": true,    // fenced blocks do need surrounding by newlines
+  "MD033": false,   // inline html is required
+  "whitespace": false  // extra whitespace is ignored, so we don't enforce it.
+}