Update {{cookiecutter.project_name|lower}}.8

- Do not use $Mdocdate$ because support for that is an
.Ox
extension.

- Wrap lines after a period so that *roff can apply French or American spacing depending on the users’ choice.

- Add a possibly missing “the” article.

Thanks for using mdoc(7) – https://www.mirbsd.org/man7/mdoc – in the first place. I went here wanting to “tune” your manpage sample, fearing I’d have to convert it from man(7) first and having to argue for a switch to modern mdoc…