Add issue template

[afuetterer]

Hi there,

I will add community wide issue templates for bug reports and feature requests at https://github.com/rdmorganiser/.github/issues/2.

These will be shown in every repository of the rdmorganiser organization, that does not have its own template.

The templates are related to the software development of rdmo and its plugins, which might not be suitable for the catalog repository.

So I suggest you create your template to override the organization wide template.

Let me know if you need help with this.