Add more details to the readme

Signed-off-by: Morris Jobke <hey@morrisjobke.de>

README.md

@@ -1,3 +1,12 @@
 # Start
 
-Run `hugo` and then serve the folder `public` on a webserver.
+Run `hugo` and then serve the folder `public` on a webserver.
+
+This can be accomplished by running this command:
+
+```
+hugo server
+```
+
+and open [http://localhost:1313/](http://localhost:1313/) in the browser.
+