Add info on how versioning works in tahoe backup

[aldeka]

Probably should add it to how_it_works and then link via an anchor to its respective feature.

Via Lou's feedback.

[daira]

Merged #79 into this.

[zookoatleastauthoritycom]

I got some more feedback on this from Myers, who wrote: "from the front page of your site I can't find some easy to copy and paste directions to backup more stuff, or restore it or see how much I've used"

[zookoatleastauthoritycom]

What would be best for you? [20:24] Something I can put in a startup script to start the daemon, clear directions what to do to make an incremental backup to put in crontab, clear directions of what I need to do to be ready to recover the backup, clear directions how to restore that backup [20:27] clear directions on how to find out how close to 350GB I am

[zookoatleastauthoritycom]

the backup cronjob should be built to not pile up as I'm guessing it's going to take more than 24 hours for this first run to finish [20:32] and if you have that built in you should put that in the documents

[zookoatleastauthoritycom]

If you can recover the backups without the .tahoe dir you need to put warnings in red about that [20:35] my though is to put that dir on a usb key but perhaps you want to walk folks thru gpg encrypting it [20:37] but then you need the passkey