bug#57958: configuration->documentation outputs contains some noise

[Maxim Cournoyer]

Hello,

There appears to be a small regression for the
configuration->documentation from (gnu services configuration): the
fields appear at the beginning of the output, before the start of the
fragment, which is undesirable:

--8<---------------cut here---------------start------------->8---
(configuration->documentation 'lightdm-configuration)
%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration%lightdm-configuration
@c %start of fragment

@deftp {Data Type} lightdm-configuration
Available @code{lightdm-configuration} fields are:

@table @asis
@item @code{lightdm} (default: @code{lightdm}) (type: file-like)
The lightdm package to use.

[...]
--8<---------------cut here---------------end--------------->8---

It'd be nice to fix that.

Thanks,

Maxim