docs: update urls for custom domain setup

- Updated all URLs to the demo page to point to `demo.pillarbox.ch`
- Updated all API documentation URLs to point to `web.pillarbox.ch/api`
- Updated all URLs to the theme editor to point to `editor.pillarbox.ch`
- Updated all URLs to the web suite demo to point to `plugins.pillarbox.ch`
- Updated all URLs to the marketing page to point to `www.pillarbox.ch`
- Updated all URLs to the Android documentation page to point to `android.pillarbox.ch`

docs/README.md

@@ -6,7 +6,7 @@ This is a demo application for the [pillarbox-web](https://github.com/SRGSSR/pil
 SDK that extends the functionality of video.js. You can use this demo to see how `pillarbox-web`
 works and how to integrate it into your own web projects.
 
-The latest demo build is also accessible here: https://srgssr.github.io/pillarbox-web-demo/
+The latest demo build is also accessible here: https://demo.pillarbox.ch
 
 ## Requirements