[Feedback]: rsnapshot issues

### Page URL

https://documentation.ubuntu.com/server/how-to/backups/install-rsnapshot/

### Select an option

- [ ] I found what I was looking for
- [ ] I couldn't find what I was looking for
- [ ] I found the information, but it was incorrect
- [ ] I found the information, but it was incomplete
- [x] I found the information, but it was confusing
- [ ] I encountered a technical issue (e.g., broken link, image not loading)

### Issue Description

a) In "Number of backups to keep", the docs show a daily/weekly/monthly configuration, but that does not match what is in the config file, which has:
```
#########################################
# BACKUP LEVELS / INTERVALS #
# Must be unique and in ascending order #
# e.g. alpha, beta, gamma, etc. #
#########################################

retain alpha 6
retain beta 7
retain gamma 4
#retain delta 3
```
The documentation should make it clear if those "alpha", "beta", "gamma", are to be replaced with the suggestion, or if the suggestions are to be added. To add to the confusion, the numbers for each retain category are exactly the same in the config file, and the suggestion:
```
retain daily 6
retain weekly 7
retain monthly 4
```
Just the names are not.
Finally, the comment in the existing file says that these entries must be in ascending order. Does that mean ascending in their name, or in their value?

b) tabs vs spaces
Nowhere in the page it says that tabs are mandatory. I edited the file without using tabs, and when running the config check, I got:
```
ubuntu@r-doc-sprint:~$ sudo rsnapshot configtest
----------------------------------------------------------------------------
rsnapshot encountered an error! The program was invoked with these options:
/usr/bin/rsnapshot configtest
----------------------------------------------------------------------------
ERROR: /etc/rsnapshot.conf on line 264:
ERROR: backup root@r.lxd:/home r.lxd/ - missing tabs to separate words - \
change spaces to tabs.
ERROR: /etc/rsnapshot.conf on line 265:
ERROR: backup root@r.lxd:/root r.lxd/ - missing tabs to separate words - \
change spaces to tabs.
ERROR: ---------------------------------------------------------------------
ERROR: Errors were found in /etc/rsnapshot.conf,
ERROR: rsnapshot can not continue. If you think an entry looks right, make
ERROR: sure you don't have spaces where only tabs should be.
```

It is written at the top of the file, but should also be reinforced in our documentation.

c) remote machine access
Our docs say that the only thing that needs touching in the config if a remote machine is to be backed up is `ssh_args` **if** the remote port is not the default.
Turns out we also need to define `cmd_ssh`:
```
ERROR: /etc/rsnapshot.conf on line 264:
ERROR: backup root@r.lxd:/home r.lxd/ - Cannot handle root@r.lxd:/home, \
cmd_ssh not defined in /etc/rsnapshot.conf
ERROR: /etc/rsnapshot.conf on line 265:
ERROR: backup root@r.lxd:/root r.lxd/ - Cannot handle root@r.lxd:/root, \
cmd_ssh not defined in /etc/rsnapshot.conf
```

d) scheduling backups
The documention again refers to an existing file in /etc/cron.d/rsnapshot, but it has different contents. The contents shipped with the package are:
```
# 0 */4 * * * root /usr/bin/rsnapshot alpha
# 30 3 * * * root /usr/bin/rsnapshot beta
# 0 3 * * 1 root /usr/bin/rsnapshot gamma
# 30 2 1 * * root /usr/bin/rsnapshot delta
```

Start with the linked rsnapshot documentation page and compare its examples with /etc/rsnapshot.conf and /etc/cron.d/rsnapshot. Run the documented config check while verifying retain ordering, tab requirements, remote cmd_ssh settings, and shipped scheduling entries. Done means the page accurately explains these differences and required configuration.

Written by the indexing model from the issue text.