Move sirv-cli to dev deps

README.md

@@ -44,7 +44,11 @@ To create an optimised version of the app:
 npm run build
 ```
 
-You can run the newly built app with `npm run start`. This uses [sirv](https://github.com/lukeed/sirv), which is included in your package.json's `dependencies` so that the app will work when you deploy to platforms like [Heroku](https://heroku.com).
+You can run the newly built app with `npm run start`. This uses [sirv](https://github.com/lukeed/sirv), which is included in your package.json's `devDependencies`. When deploying to platforms like [Heroku](https://heroku.com), ensure `sirv-cli` is a production dependency.
+
+```js
+npm install --save-prod sirv-cli
+```
 
 
 ## Single-page app mode

package.json

@@ -13,9 +13,7 @@
     "rollup-plugin-node-resolve": "^5.2.0",
     "rollup-plugin-svelte": "^5.0.3",
     "rollup-plugin-terser": "^5.1.2",
+    "sirv-cli": "^0.4.4",
     "svelte": "^3.0.0"
-  },
-  "dependencies": {
-    "sirv-cli": "^0.4.4"
   }
 }