Update openSUSE download URL

I no longer maintain the openSUSE packages, but several other contributors are doing it. Changing the URL to the appropriate search on software.opensuse.org is much more reliable.
Merge pull request #41 from cbosdo/patch-1

Update openSUSE download URL
Fix typo
Add Mageia
Merge branch 'website' of github.com:Kozea/Radicale into website