Update prettier config to support MDX and reformat all files

Author: Andrey Okonetchnikov

.prettierrc

@@ -2,7 +2,7 @@
   "useTabs": true,
   "overrides": [
     {
-      "files": "*.md",
+      "files": ["*.md, *.mdx"],
       "options": {
         "printWidth": 70,
         "useTabs": false,
@@ -11,4 +11,4 @@
       }
     }
   ]
-}
+}

README.md

@@ -1,2 +1,3 @@
 # ds-101-workshop
+
 Design Systems 101 Workshop

package.json

@@ -8,7 +8,7 @@
     "posttest": "npm run format",
     "slides:start": "mdx-deck ./slides/ds101-worskhop.mdx",
     "slides:build": "mdx-deck build ./slides/ds101-worskhop.mdx -d ./build/slides --basepath /slides",
-    "format": "prettier --loglevel warn --write \"**/*.{js,css,md}\""
+    "format": "prettier --loglevel warn --write \"**/*.{js,css,md,mdx}\""
   },
   "repository": {
     "type": "git",