Add note how to easily add date as suffix in bash

[claell]

Reading the docs, I wondered how this can be achieved.

Might not be wanted as part of the docs, though.

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• I have read the contribution guidelines.
• I have added tests for all changes in this PR if appropriate.
• I have added documentation for the changes if appropriate.
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[claell]

I just quickly ticked all checkboxes, but didn't really check. After getting feedback, whether this addition to the docs is okay, I'll be happy to comply with the repository requirements for commits and pull requests.

[albertony]

I think its ok to include as an example. Two comments/questions:

• Is it really bash-only? Or is date a standalone utility, independent of the shell, and works on all/most Linux - even Mac? I'm asking, because I don't know. If so, I see that unfortunately we use a mix of terminology in the docs to cover these, including "Linux/macOS", "Unix systems (Linux, macOS, …)", "Unix systems", "unix like platforms", which could have been cleaned up abit, but for now maybe just pick one... :)
• Is the format %F fixed, or is it depending on regional settings? From forum I've seen %Y-%m-%d which are more explicit, but if %F is definitively always equivalent then that's better.

PS: On Windows, if using PowerShell, one could achieve the same with $(Get-Date -Format 'yyyy-MM-dd').

[ncw]

Looks nice - thanks! I would be explicit though and write

In bash, this can be done with `--suffix $(date +%F)`.

[claell]

Makes sense!

@albertony:

• I haven't checked, either. To be sure, I wrote bash, but probably it's applying to all Unix systems.
• Format: Not sure, I can check

Also nice to see a PowerShell equivalent, might add that as well.