enable IntelliSense and type checking

README.md

@@ -38,7 +38,7 @@ Inside of your Astro project, you'll see the following folders and files:
 └── tsconfig.json
 ```
 
-Astro looks for `.astro` or `.md` files in the `src/pages/` directory. Each page is exposed as a route based on its file name.
+Astro looks for `.astro`, `.md` and `.mdx` files in the `src/pages/` directory. Each page is exposed as a route based on its file name.
 
 There's nothing special about `src/components/`, but that's where we like to put any Astro/React/Vue/Svelte/Preact components.
 

tsconfig.json

@@ -1,6 +1,7 @@
 {
     "extends": "astro/tsconfigs/base",
     "compilerOptions": {
-        "strictNullChecks": true
+        "strictNullChecks": true,
+        "allowJs": true
     }
 }