feat(markdown): enable Satteri authoring features

www/package-lock.json

@@ -6,6 +6,7 @@
     "": {
       "name": "arizona-institute-for-autism",
       "dependencies": {
+        "@astrojs/markdown-satteri": "^0.3.5",
         "@astrojs/mdx": "^7.0.5",
         "astro": "^7.1.5",
         "cheerio": "^1.1.0",