[meta-request] Clarify bug-reporting instructions in readme

[Variance Quorum]

My game is frequently hanging, and I came to report the behavior. In issue #7653, @Brian Bucklew writes

can you post a player log from a hang?

In my experience as an OSS developer, I find bug report quality from users is greatly improved by making this sort of policy visible front & center, with detailed instructions for the users to generate useful dumps. In my inexperience with the guts of Qud, I’d really appreciate these instructions because I would like to file a useful report.

Thanks!