Build should not overwrite existing documentation

[JensGJ]

I'm struggling to find the right way to use the documentation part of the template.

Every time I build the module (based on the template) the documentation files are created from scratch - overwriting any changes I have made to them. I haven't been using platyPS outside of this template, but I hope that the fix might be as simple as calling Update-Markdownhelp instead of New-Markdownhelp.