Hi,

I was looking for a "multiple news fragments of the same type linked to one issue" functionality, and I found it through #355 and #119, but unfortunately it doesn't seem to work with the towncrier create command:

$ towncrier create 2585.changed.1.md
Usage: towncrier create [OPTIONS] FILENAME
Try 'towncrier create --help' for help.

Error: Invalid value: Expected filename '2585.changed.1.md' to be of format '{name}.{type}', where '{name}' is an arbitrary slug and '{type}' is one of: feature, bugfix, doc, removal, misc

It does seem to work when I manually create the file 2585.changed.1.md though, so it might just be the problem with the command not supporting it?

Also, if this is a supported feature (which I think it is, based on https://github.com/twisted/towncrier/search?q=counter), it would be nice to mention it somewhere in the docs.

I'm happy to help with a PR if needed.