Hint to new userconfig file for ssh servers in headless setups.

[gituser789]

The new headless setup was introduced into the documentation.
But this hint was missing in the ssh-server section.

A user just looking into the ssh-server part does not know about this new feature, which was introduced april 2022.

[aallan]

We tend not to add specific dates into the documentation as this ages quickly into being irrelevant information.

[gituser789]

Updated according your hint.

Build failed

[aallan]

Automated build fails, please correct the errors and we'll look at the PR again.

Traceback (most recent call last):
  File "/home/runner/work/documentation/documentation/scripts/create_nav.py", line 123, in <module>
    raise Exception("{} has an internal-link to {} but that destination doesn't exist".format(filepath, linkinfo['url']))
Exception: documentation/asciidoc/computers/remote-access/secure-shell.adoc has an internal-link to computers/headless.adoc but that destination doesn't exist

[gituser789]

internal linking is fixed

[gituser789]

Hi,
i fixed the internal linking. Can you review the PR again?

[aallan]

There is not an application called "Configuring a User"?

[gituser789]

Updated.

[gituser789]

One link was changed by mistake, this was reversed.

[gituser789]

Sorry for some trouble. May it is possible to run the tests before the review?

The documentation linkin should work like
main-adoc-file.adoc#section[name]

I was mixing different link styles. I updated it now to
configuration.adoc#configuring-a-user[Configuring a User]
and the section [[configuring-a-user]] was introduced inside headless.adoc, what is linked in configuration.adoc

Please review again.