[RFC] Mandatory user doc in KDE review/incubation checklist

Hi,

Since we restored docs.kde.org, I would like to propose to add a new
item in the checklist [1] for new projects (rewording welcome if
needed):
- [ ] User documentation in docbook format should exist in a doc (or
docs) folder

For now, the only item close to it in the KDE Review checklist is:
- [ ] Documentation appropriate to the project: if a library, API
documentation (such as [Doxygen](https://www.doxygen.nl/) for C++), if
an application, user documentation (such as a README detailing what
the application does or is for, how to install/build, and other such
useful information)

But it is not explicit enough about the format.

What do you think?
Cheers,
Johnny

[1] https://develop.kde.org/docs/getting-started/add-project/