Broken link to cvmfs doc

[zlmarshall]

Hi there,

https://swan.docs.cern.ch/cernbox/sync_files/

links to:

https://cernbox.web.cern.ch/cernbox/en/synchronisation/

which doesn't exist. Maybe it should be:

https://cernbox.docs.cern.ch/desktop/sync-client/

?

Cheers,
Zach