feat: add mdx support (#845)

Author: avivkeller

package-lock.json

@@ -1,7 +1,7 @@
 {
   "name": "@node-core/doc-kit",
   "type": "module",
-  "version": "1.3.10",
+  "version": "1.4.0",
   "repository": {
     "type": "git",
     "url": "git+https://github.com/nodejs/doc-kit.git"
@@ -74,6 +74,7 @@
     "rehype-recma": "^1.0.0",
     "rehype-stringify": "^10.0.1",
     "remark-gfm": "^4.0.1",
+    "remark-mdx": "^3.1.1",
     "remark-parse": "^11.0.0",
     "remark-rehype": "^11.1.2",
     "remark-stringify": "^11.0.0",