Add doap file

This adds a .doap file to this repository, as GNOME's translation platform Damned Lies seems to be reading phosh's doap file and setting the issue tracker to phosh's in the chatty's page and in the PO files' Report-Msgid-Bugs-To field.

Regarding doap files, see Git/FAQ on GNOME Wiki for more info.

I'm made an educated guess on description and maintainer. Please let me know if something should be fixed.