Create paper-plugin.yml

Create paper-plugin.yml if Paper breaks plugin.yml parsing.

Paper now explicitly identifies Paper plugins in the /plugins command, by the existence of paper-plugin.yml. For example

> plugins
[14:44:31 INFO]: Server Plugins (158):
[14:44:31 INFO]: Paper Plugins:
[14:44:31 INFO]:  - ChessCraft
[14:44:31 INFO]: Bukkit Plugins:
[14:44:31 INFO]:  - AcceptTheRules, ...