Hm, sounds quite nice. Our copying.md file is to track the actual copyright holders of the code, so it's not suitable for bugreports and other contributions.

That said, I imagine it is very hard and a high overhead to keep track of all non-code contributions and to add them. So I'm not sure what the value opposed to the needed effort for implementing this is.

So far there seems no demand to implement this, so I'll close this for now. That said we're of course thankful for all contributions including bug reports etc.
Keeping track of all people requires much much time that I'd rather like to spend on actually improving the codebase. Anybode else can step forward though and do this.