Updates for index-v2

This needs to changes to the fdroid config.yml:

• repo_url/archive_url need to be valid:
  repo_url: https://f-droid.org/fdroid/repo (instead of https://f-droid.org/repo)
  archive_url: https://f-droid.org/fdroid/archive (instead of https://f-droid.org/archive)
• repo_web_base_url: https://f-droid.org/packages/