- deleted Starter documentaion.md
no need for .md-file, there are several links to it in other docs here
- deleted folder about additional UB campaigns, the svn-link inside wasn't working anymore
- updated links in other files
- added some comments in other files
- added link to discord
- updated link for download latest 1.13 and deleted outdated or unofficial ones (i.e. maeyeanie)
