[Borgbackup] recommended check option

[Thomas Waldmann]

Wow, that took long.

Interrupted backup (connection issue, transport endpoint not connected): 
just start borg create again and again in the same way. It won't 
transmit the data again which it already has in the repo. For this, a 
"borg check" is not needed.

I/O Error: fs or storage device malfunctioning, if you have access, run 
a SMART long test on the disks and check the SMART status/logs (smartctl).