Update deploy instructions

Author: avivace

README.md

@@ -2,6 +2,21 @@
 
 This is the CoderBot documentation repository.
 
+Start a development server with hot reload on `localhost:8080`:
 ```bash
-./node_modules/vuepress/vuepress.js  dev pages/
+npx vuepress dev pages/
 ```
+
+Production build:
+```bash
+npx vuepress build pages/
+```
+
+There's an npm script to deploy on GitHub pages from the `master` branch. Run 
+
+```bash
+npm run deploy
+```
+
+And be sure to have setup GitHub pages to serve the `master` branch.
+