added build-time information

docs/development.md

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+## Developer Setup
+Clone the repository
+```bash
+git clone https://gitea.virtonline.eu/2HoursProject/nexus-timer.git
+cd nexus-timer
+```
+Run the live update server locally
+```bash
+npm run dev
+```
+### Modify the app
+Make code changes...
+### Test the PWA locally
+Open it in your browser:
+[http://localhost:8080/](http://localhost:8080/)
+### Commit & Push
+Stage changes, commit and push
+```bash
+git add .
+git commit -m 'My cool feature'
+git push
+```