example blog add buildoptions (#142)

* examples: add astroRoot to blog example

* example: add astro config for `npm run build` #141

examples/blog/astro.config.mjs

@@ -1,3 +1,10 @@
 export default {
-  site: 'https://muppet-blog.github.io/',
+  projectRoot: '.',
+  public: './public',
+  dist: './dist',
+  buildOptions:{
+    sitemap: true,
+    site: 'https://muppet-blog.github.io/',
+  },
+  astroRoot: './src',
 };